Well it mostly comes down to personal taste, but since you ask for opinions i'll share mine with you.
Ice/ice!!
Espcialy when you wanna get to pvp with your dom. The slows and -recharge really are ace in pvp. Also powerboost is really, really sweet.
I have a fire/ice at mid lvl and an ice/nrg and plant/fire at high lvl. I wish now i had made an ice/ice (the grass is always greener... 
I'm quite gutted with the nerfs to the pets. My imps usually don't last long (especially in big teams with big spawns) against most +2 or higher mobs and I even have aid other so i can heal them when really needed. Imps are hurt most by this nerf since they are so squishie already. This is especially the case for domi's as they lack true defensive powers or buffs.
Fire control is nice, but the imps just don't cut it anymore when fighting tough mobs and you lack any secondary effects. The imps die a lot...
Ice control has excellent recharge and speed debuffs. AA is just a godsend! And Jack is pretty sweet. He has a very nice CE (killer in pvp when you can get him next to your opponent!) -btw imo better drop this power from your domi as most of times it's hard to handle the agro it generates and the PBAoE is rather small, making you still vulnerable to ranged attacks which you'll be getting a lot more- and gives good support with holds, slows/recharge and pretty nice damage, albeit being a slow bugger :P
Fire/fire is good damage, but lacks in the debuffing and controlling department which ice/ice can bring and imo that is what makes a domi shine. Ice/ice is far better in that. And icy assault still feels very nice with decent dam and fast attacks, just not the good AoE dam fiery assault has to offer.
PvP wise there's no escape: ice/ice rocks!
Well ive rolled both toons and they are both up to lvl 14, and i still cant decide, i think ill probably stick with fire now.
Dark Fire Storm
From your choices, I'd go for Ice/Ice. I personally love the Fire primary, the control is great and fast and the Imps are still quite brutal, but since you want to PvP -- Power Boost, single target focus and the -recharge tip the boat to Ice's favor.
[b][color=blue]Coldest War /[color=red]/ Omega Patient[/b]
[url="http://www.the-cow.net/"][color=red]The CoW Network (Blog) /[/url][url="http://www.collegeofwar.com/"][color=blue]/ College of War[/url]
Nobody seems to have mentioned this yet but Fire for a Dom is awful in PvP. I have one (Fire/En) sitting at lvl 47 at the moment. He is great fun in PvE and is a bit of a powerhouse, I can easily solo on relentless without usually breaking a sweat.
Forget about PvP with this toon. Fire Control lacks any of the soft controls that the other primaries have and this is what really lets it down for PvP. If you want to be able to stand a chance in PvP then pick Ice.
The one thing that Fire Control has in for PvP that seems to be constantly overlooked by people who focus their eyes on secondary effects, is the fact that the ST Hold is damn fast-firing. 1.07s activation time compared to Ice's 1.87s. That .80 seconds every time you fire a hold can be a huge difference.
[b][color=blue]Coldest War /[color=red]/ Omega Patient[/b]
[url="http://www.the-cow.net/"][color=red]The CoW Network (Blog) /[/url][url="http://www.collegeofwar.com/"][color=blue]/ College of War[/url]
Most of the time holds are not the way to win PvP battles. Therefore a faster activation time for the hold will do very little for you. The "huge difference" will be that you maybe waste less time before resorting to other tactics.
Ice has some forms of control that are less likely to be resisted and will help a lot more in an average PvP battle. Fire has nothing like that, so I have to vote for the ice dominator.
If it has eyes, you can blind it, if it has blood, you can make it bleed, if it has a mouth, you can make it scream.
Ok im really stuck.....I have -
lvl 13 ice / ice Dom
lvl 6 fire / fire Dom
Im really stuck on which one to lvl 1st, i dont have the time to do them both....
I love them both tho, ice seems really cool with the slows and AA nd CE, im getting on quite well with it so far, doing well.
But the fire dom looks cooool, all that damage and the lil imps running around causing so much damage
I dont know what to do, im in a sticky situation.... I do like PvP as i think when i get to lvl 50, thats most of what i will be doing...
I tried rolling a fire / ice as i get the best of both :S:S or do i??? it just didnt feel quite rite, the holds not as good, i know PB can help that but, hmmmmmm!!!
Can anyone help me... Some views on both sets and stuff please???
Any help would be great!!
Jamie...