The infamous war troll, center of the Emerald Legion exploit. If you haven't read it yet, I highly recommend it as an interesting theorycrafting exercise, as well as the sheer ridiculousness of it all (the first section contains the phrase 'have the semi-living zombie Troll males mate with the normal War Troll females', just to give you an idea).
Anyway, the war troll. Notably, and unlike the other trolls, those are monstrous humanoids rather than giants. For the most part, the types are equivalent, but monstrous humanoid gives full BAB. This means the war troll gets three BAB over a giant of equal RHD (which could translate to as much as +6 or +12 damage on each attack), as well as an additional attack.
Furthermore, war trolls have the beefy chassis expected of a troll. They get +20 strength, +18 constitution, Large size, and an okay bite attack for good measure. On top of that, war trolls enjoy Spell Resistance 20, DR 5/adamantine, and Regeneration 9 overcome only by acid damage.
They also get the useful Dazing Blow, which turns all of their weapon attacks (RAW says bites count too, RAI implies they don't) into save-or-sucks with a constitution-based save DC. It lets war trolls all but neutralize certain enemies, and more importantly gives them impressive ranged utility with relatively little investment (thrown weapons count, so if your enemies are at range you can fling a few daggers and mess them up with dazes).
While I'm a bit hesitant to give a 12 RHD bruiser +0 LA, I think the war troll will contribute to a party just fine. Dazing Blow is amazing, the chassis is good, and regeneration is always nice to have. +0 for now.