the hifonics puts out more watts and is cheaper and heres a link to get it even cheaper w/free sh+h
In my opinion, Soundstream has always made good products, especially amps.
Any decent 4-channel with an RMS of 25 to 75 per channel would be great. Alpine, Soundstream, Fosgate, Kicker, HiFonics, JL Audio ... Amps like this. If you intend to use a subwoofer, get a 4-channel with a high-pass crossover and set it around 80Hz.