What kind of games do you run mostly? Eight gigs is fine right now for just about everything. Only a handful of applications, like a heavily modded Skyrim for example, are starting to use more. Since I just started playing Skyrim myself I might personally go with 16GB (which would require you to upgrade to a 64bit OS as well). The only concern I would have is that DDR4 is supposed to hit the consumer market towards the end of this year...maybe. Well, it's a tough call really. The release time-frame isn't set in stone and it will almost certainly be overpriced at the beginning AND it's going to require, at the very least, a new motherboard.
Anyway...as for brand-names, I trust Corsair, Mushkin and Samsung. G.Skill is another popular brand among gamers but I have not personally used them before.