i hate to give out amp/speaker recomendations because i can promise you that anything i like and recommend, someone else will hate, and recommend a completly different brand--it is like asking a group of car buffs what the best car in the world is.. there is no correct answer, and you will probably leave more confused than before.
i would prefer to try to help you understand what makes the amps different, so you can pick the best amp that fits your needs, and more importantly, your budget.
watts is the power that the amp puts out-- the more watts, the more power(too much will hurt the speakers though)
ohms is a measure of resistance-- the resistance of the speaker-- most speakers are 2,4,6,or 8 ohms.
most subs are 2 or 4 ohms.
in general, the higher the speakers resistance, the better, and cooler the amp is going to run, but the less power it is going to put out, becasue of the extra resistance.
when looking at amps and speakers, always compare the 'RMS Wattage' of the two(the max wattage rating varies by manufacturers testing process, and is mostly unreliable), and try to match them as close as possible.
also, just wanted to comment on those pyle square subs: i have had a chance to look at those and compare them with the kicker L5/L7's they are modeled after-- the pyle version does not have a ribbed surround on the corners of the cone, making the cone travel less distance, and hurting the overall performance of the sub. i was actually highly dissapointed in that-- because i had been interested in using them in a small pickup install(i wnet back to a spare kicker round sub i had laying around).
overall, i would recommend a round sub of any brand over the cheap square subs-- because there is alot of work that square subs need to work properly, and i just don't see it in that sub.