just under 400fps is golden for AEGs for outdoors play if you're looking to max out and still be able to play at most fields.
just under 300fps if you want to play at ANY field, indoors or out.
FPS isn't the only factor, nor is it the largest factor, in a gun's performance. Once it's high enough to be felt by people at a decent distance (~300 for outdoors, or 250 for indoors), then it usually only increases the amount your gun breaks, and how much you hurt people.
FPS helps when:
People can see you firing, the higher the FPS, the less time they have to dodge the BB flying at their head.
You are shooting uphill or downhill at angles of over 10 degrees or so. (Hop-up is affected by significantly sloped shooting)
Honestly, you shouldn't be shopping for guns based on FPS, accuracy, reliability, and it's ability to accept upgrades and replacement parts are the key factors.
If you're looking for it to be as cheap to play while still being competitive, don't get guns that are shooting ridiculously hot, as these often require you to use heavier (more expensive) BB's to perform correctly. ~350 I think is a good balance for all-around playability. TAC and MTT both have a 420fps limit (MTT's is technically 375 with a .25, which equals 419.97fps with a .20), most AA games have a 400FPS limit for full auto, while some provisions are occasionally made for single-shot and semi-auto only guns to shoot hotter.
I have a 280fps AK74 that gets people out just as well as my 510fps SR16. FPS is NOT king. I just use the SR at fields that are extremely hilly and don't like for people to dodge the BBs since it's only semi-auto, I can't spray and pray. Gotta hit them the first time. lol.
