Well im using Kenwood amp thats the exact same model style as the stock one, except I have the bigger one. You want to look at the RMS ratings to amps and subs not the max. So my setup right now is a 300 rms amp matched to a 250 rms infinity 10'' sub. Its a good idea to have an amp that has more RMS watts than the sub. Safest way to keep the amp from overheat, since amps are way more expensive than subs. So the stock amp is 120 RMS and the JL w3 is 250 RMS thats why the amp will overheat trying to push a sub thats more than double the wattage. Thats why i said if you dont blast the jl w3 with the stock amp you should be fine.
As for other subs that could work. I would deff stick with JL its by far the best sub brand IMO. Ive had Kicker, MTX, Infinity, Memphis, Kenwood. But I've used a jl w1 10'' sub its a pretty solid sub. So if you want to go with a JL w1 it would probb be easier for the stock amp to handle and you wouldnt need a spacer.