i was just asking myself the same question a couple of weeks ago! After 2 weeks of reading infinite amounts of threads. I decided on the following:
1. mtx thunder 404 (didnt like the looks, cost the least) 2. infinity 7540a (was really big - 17"!!!) 3. audiobahn a4004t (all threads point to NOO!) 4. alpine mrp-f240 (no spkr level inputs) 5. jl audio 300/4 (slash series) (no spkr level) 6. jl audio e4300 (e series) (less wattage 45x4) 7. kenwood kac-8401 (didnt like hte looks) 8. audison vr404.4 (WANTED TO GET THIS ONE!!! from all the praises i heard about it, but cost $$$)
My requirements were: 1) as high a wattage as possible ofcourse 2) Must have preamp outputs 3) Must have speaker level input 4) specs. like Signal to noise, THD, and Size
I chose the JL Audio e4300, b/c it met all my requirements as some of the other did, but it had better specs. than MTX, Infinity...), and it looks nice. I almost bought the Infinity 7540a but changed my mind in the last minute, even though there werent really any neg. posts about the infinty there were a lot of positive post on the JL amps in general, not the model i got.
I bought mine from Ebay for $210 + $20 Shipping, it is NEW). I just ordered it so i cant tell u much about it, i havent recieved it yet)
Hope that helps, from one beginner to another.
P.S. If you have the money and dont need spkr level inputs get the Audison and (almost) everyone else will be a step below you. :-)