PvP /rad does way better. For PvE their both awesome.. Most people might prefer rad because of LR, but honestly Dark is a great choice (got great debuffs, AoE rez that is also a great debuff+disorient, stealth with nice resists, fear, a pet and great heal power). I think I'd go Ice/Dark.. I always try to play the less common build when I'm in doubt 
@False Fiction - Virtue / Defiant
Current projects - [Glaciologist - Ill/Cold Troller] [Cloudshaper - Storm/Dark Def] [Harald Wartooth - Elec/Psi Domi]
Tar Patch and Ice Storm will also synergise beautifully!
G-Force
Go Fire/Dark! 
PvP wise ice/rad is much better. PvE both are great.
Pfft Ice/Kin ftw . .
Both Ice/Dark and Ice/Rad are great though so go with personal preference.
thePhilosopher Martial Arts/Regen/Fire Scrapper
theRegulator Empathy/Energy/Soul Defender
Total Inertia Ice Blast/Kinetics/Psy Corruptor
Total Inferno Ice Blast/Thermal/Leviathan Corruptor
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Pfft Ice/Kin ftw . .
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Obviously
I#ve got an ice/dark for PvP and he's a lot of fun to play - many tricks up the sleeves. Tar patch and ice storm is great combination in both PvE and PvP. By 50 you'll have 3 single target holds available but I find I don't need them at all; the terror and howling twilight are actually better.
End is such a huge problem that you need to manage which toggles you need on quite carefully - shadowfall, acrobatics, darkest night and travel powers aren't always needed so turn them off if you can!
IN MEMORIUM OF GAYBABY
CRUELY TAKEN FROM THIS WORLD WHILE SO YOUNG
I realise this is actually an old post anyway, but just to back up what Irradiator is saying... Ice/Dark is very nice in PvP, and I really wouldn't say that Ice/Rad is the clear choice, on that front.
I keep meaning to write an Ice/Dark guide at some point, seeing as I've probably played it more than any other combination, by this point. It's a really fun and powerful build, and has a lot to offer solo, in teams, and in PvE or PvP. If you play anything like me, though, it is 41 levels of pain as you run out of endurance over and over, until you get Power Sink from Scirocco, and maybe some SHOEs to help the lack of slots problem.
IMO Ice/Rad only does better at PvP cuz the two main debuffs are toggles while Tar Patch is a click zone debuffer (however I do love this power and it is one of my fav in the whole game). Again, my vote goes for Ice/Dark.
@False Fiction - Virtue / Defiant
Current projects - [Glaciologist - Ill/Cold Troller] [Cloudshaper - Storm/Dark Def] [Harald Wartooth - Elec/Psi Domi]
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IMO Ice/Rad only does better at PvP cuz the two main debuffs are toggles while Tar Patch is a click zone debuffer (however I do love this power and it is one of my fav in the whole game). Again, my vote goes for Ice/Dark.
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In the zones, I tend to find people get away from toggles too easily, or drag them into groups of mobs, getting you a ton of aggro. I certainly make heavy use of Darkest Night anyway, but I don't find toggles to be enough on their own. The extra control offered by Dark makes it really quite good in large areas - I'd rather have Fearsome Stare when I'm doing zonal PvP than just about anything in Rad. Having two quick-firing holds lets you stack over people with Acrobatics (sure, there's Bitter Freeze Ray and Patron holds, but the former takes too long to fire off, and the latter has a long recharge, and comes very late on). And while it can be more difficult to get someone in Tar Patch than Enervating Field, again, at least they can't just fly away until the toggle drops. Tar Patch is quite nice in PvP on the occassions you go get someone stuck in it - I've found it pretty nice against Tanks who think they're okay standing their group. Being in the arena, rather than a zone, could change matters, although as with many sets and builds, it depends on the map.
I just hate to see people write off Dark in favour of Rad immediately when it comes to PvP, as both sets have a lot to offer, just in different ways.
for PvP, rad probarbly does better because the acc debuff is much stronger and end is easier to manage.
IN MEMORIUM OF GAYBABY
CRUELY TAKEN FROM THIS WORLD WHILE SO YOUNG
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for PvP, rad probarbly does better because the acc debuff is much stronger and end is easier to manage.
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If the numbers in the builder I have are anywhere near correct, which I know is entirely iffy (as are most numbers you see floating around, far as I can tell ), Dark can stack up more tohit debuffs than Rad can. Drop the toggle on, fire off Fearsome Stare, and you have more tohit debuff, a damage debuff, and a terrify on the person. Then the heal does a small debuff, too.
Anyway, not to get into an "X is better than Y!" discussion because it's a bit pointless, and not really quantifiable in this case - the main point is they're both fantastic sets, and you can't really go wrong either way. I'd just go for the one I find more enjoyable to play in that kind of decision, as they're both good in PvP and PvE
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Anyway, not to get into an "X is better than Y!" discussion because it's a bit pointless, and not really quantifiable in this case - the main point is they're both fantastic sets, and you can't really go wrong either way. I'd just go for the one I find more enjoyable to play in that kind of decision, as they're both good in PvP and PvE
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Amen to that Cyber 
I personally prefer /dark over /rad on a given toon. I find it more interesting and satisfactory to play and has a better feel for me. /rad is certainly easier to manage and more fire and forget uber (boring ), whereas /dark demands more skill in positioning, targeting and timing. It's more nifty and as mentioned earlier has 'tricks up his sleeve.' When played to excellence it can be just as dangerous as /rad but definately more satisfying.
That's pretty much how I feel. I do actually have three Rads, but I don't find any of them as fun to play as my Ice/Dark. Dark Miasma is a very active set, there's a lot of control, and I really enjoy the feeling of having multiple ways to deal with things. Rad tends to get a little samey for me after a while, and I get bored.
Both sets have -res, -dam, -acc.
Rad has -rech, -spd, end drain resist, mez resists (not protection), end recov boost, damage boost, -def, end drain, and a non-rooting heal which doesn't need a to-hit check.
Dark has... a fear, a hold, a disorient (BFs ftw?), a tar patch which noone will ever fall into unless webnaded, a pet (easy to avoid), a phase who lasts 8 seconds or so (woo hoo).
Dark might be greater than rad in some situations in SC, BB or WB when your opponents haven't tactics, fort, CM/clarity, TD and against casual players who walk in the zone without breakfrees and/or don't know to stay moving, but that's about it.
In the arena, your -acc is negated by FA, tactics, aim, build up, -def debuffs or +acc buffs, your controls are negated by break frees and they aren't strong enough to run your opponent out of breakfrees, so that leaves... your static -res, a pet and a phase. Woo hoo.
Dark isn't horrible by any means, but it's hard to claim it's better than rad in pvp if you played the two and pvped a bit.
Uh, I did say I was talking about in the zones, and that arena would be a different matter. ("Tar Patch is quite nice in PvP on the occassions you go get someone stuck in it - I've found it pretty nice against Tanks who think they're okay standing their group. Being in the arena, rather than a zone, could change matters, although as with many sets and builds, it depends on the map.") Mind you, my Ice/Dark hasn't been awful in arena, either (did decently well in the Squished tourny that was held a while back, teamed with a /Dark MM, including making a team run out of BFs which is apparently impossible), but she's definitely more of a zonal PvP toon. In arena, as I said, map matters. So does who you're fighting - like any set, Dark is going to be better against some things than others. I think you're underestimating the debuffs anyway, because I've seen a /Dark MM, with weaker debuffs than a Controller, beat a Regen with FA and Tactics running one on one in a cage match.
Also, please stop putting words in my mouth - I never said Dark was better than Rad in PvP. In fact, I said it was a senseless argument and one I wouldn't get into. I just think it's a shame people write the set off immediately when it is actually quite good, especially if you're looking for a toon for both PvE and PvP, as the original poster was.
EDIT: Also, just thought I'd better point out, so no one thinks Dark is as poor as you're trying to make out for some reason... it doesn't have a simple disorient, it has an auto-hit AoE disorient with a big -regen attacked to it. It knocks Blasters sitting in PFF out instantly, and is quite nice against Regens.
Don't we just love talking builds! 
i need some feedback on those two as i can't choose between them
how do they perform in PvP? PvE?