On the benchmark's they do test a little slower, but they are a lot cheaper. The difference between HDD and SSD performance is like going from a prop plane to a Jet, the difference between EVO and PRO is like arguing the nuances between an F16 and an F15 if you get my point, except EVO is a lot cheaper.
My advice is to go with the cheaper EVO because you pick one up for $80 on sale and in a few years from now, your going to want to upgrade from 120gb SSD to 1TB SSD once the TB SSD become an economic option like the >250Gb SSDs have and ditch the HDD all together.
From what I've read, Yes Evo stress tests slower than the Pro, but to a degree that its important really only if your worried about your benchmark score. So for the price, I like the EVO
As for brand, Samsung really kind of has taken a pretty good position in the market for SSDs. For right now Samsung is kind of like the Intel of SSDs, they have a longer track record and overall most people will automatically point you in their direction when your asking adbout quality.