It depends on what you are going for. SM/FA will be a much stronger AoE build than SM/WP, but the WP one will be much more survivable and not have any endurance problems. Of course both will be very good builds since you will have Fault. It really depends on what you want to do with your Brute.
I agree that the two will be completely different in concept and playstyle. I don't think that FA will leave you out in the cold as far as endurance goes though. The best FA builds will have loads of recharge, so consume will be available often as well as healing flames. I don't think that the survivability gap is all that great once one gets used to FA either.
To add to that, Stone melee will add some nice mitigation to whatever perceived squishiness and add some survivability to Fiery aura.
Just think about your concept and if you can stand looking at a person on flames perpetually. It's that, or look at the dull yellow glow of WP working.
Words to the wise aren't necessary- it's the stupid ones that need them.
"You're right...I forgot...being constantly at or the near the damage cap is a big turn off. Definitely not worth it."
- Vitality
My vote for Stone/WP. Stone is such an end hog, QR + Stamina is your best bet to solve end issues. And both sets synergize extremely well, Stone's KD helping WP's regen to tick freely.
Mine is just 36 with Tremor and Fault slotted, both holding a FF recharge proc. She's a blast to play !
Well, I like /Fire too, and basically, when it comes to slotting chars now, I aim for a chunk of +acc from IO set bonuses, and then focus more heavily on end reduction. if I have say 30-40% global acc bonus, I dont have to go so nuts in +acc in each power. Also, I've realized I've made many WP chars, even though making too many WP chars is like dividing by zero-doesnt work. 
I've played both to 50, and they both have their strengths and weaknesses. if you spend the money, the willpower is MUCH more survivable. no matter how you fast you can hit the heal, the %res and regen is unmatched. Dont get too wrapped up in needing the AoE's with stone. I took Assault/Tactics instead of fault/tremor. i know its unorthodox, but with all the recovery it was a good decision, and works better in teaming. I'd recommend a willpower because it IS the best brute secondary in the game (in my opinion) and its hands free, so you can focus on using your primary, and not have to 'worry' about what you need to do from your secondary. you can just attack, and be a brute.
Kaars Aerinstar
-BoP-
never...EVER...skip fault in stone melee. tremor is skippable
Unless you plan on just beating on pylons and roaming single AV's and EB's, there is no other reason to ever skip Fault...and 5 slot it at least. Fault is one of the best hard control powers in the game. They gave it to brutes, appreciate it.
Ditto - never ever ever ever skip fault. Tremor, maybe, but not fault. Best dang power in the set imo, and yes I am including seismic smash in that.
As to the stone/wp vs stone/fire question, I went stone/fire, mostly because of the AoE issue. I just wanted to actually have a bit of AoE, which /fire provides between blazing aura and fiery embrace (and concept too, but that came second). Both sets have an end recovery tool, which is very nice considering stone's end burn problems - WP's may be better, but consume isn't *that* bad. Only thing that really annoys me is that leveraging burn by taking electrifying fences would interfere with fault/tremor's KD, and the patron immobs that don't prevent KB are all cones, making them difficult to use in melee (or else have redraw, a huge cast time, and an ugly concept-breaking mace).
Plus, I think RoTP is hella cool. Yeah, it's probably more efficient to have a true tier 9 that prevents you from dying in the first place, but imo nothing says 'I'm unstoppable, bish!' like getting back up off the floor in a gigantic explosion that sends everyone flying. And who cares about debt? You're a brute - go smash a bunch of eyeballs in and the debt will go away soon enough. Honestly, that's why I play this particular combo - stone melee is just orgasmically smash-tastic in terms of how powerful the set feels (love them SMASH sound effects), and if you pair it with /fire you're a rock that is on fire and can explode! What could be cooler than that? 
@MuonNeutrino
Student, Gamer, Altaholic, and future Astronomer.
This is what it means to be a tank!
The Mu Immob prevents KD, but not disorient, so it still works to with fault AND burn. I'd also toss my two cents in for WP over fire. Fire provides more damge, more aoe, but has less end recovery by far, and supstantially less healing, except when fighting single targets.
Fire Rules at single target, WP rules at multitarget. Purely from a survivability standpoint.
I agree never skip Fault unless you have a fighting style that does not need it. Or other mitigation that does not require it.
Most of the time you need the mitigation it brings. If your new to stone take it and Rock on.
Pinnacle
Arch light L50 INV/SS
Psiberia L50 Kin/Psi
Screaming Mentallica L50 Sonic/MM
Infinity
Arc Voltinator L50 SS/Elec
Mind Fire Kinesis L50 Fire/Kin
Flaming Screamer L50 Fire/Sonic
Thoughts, discussions?