I own both, a S&W M&P1522 and a Tippmann M4-22. Both function very reliably with a broad spectrum of ammo, including all the everyday name brands you can think of. I prefer CCI Mini Mags or AR Tactical. Neither have exhibited outstanding accuracy, but both shoot tight enough groups at 50 yards to make a beer can dance until it is so well ventilated that most bullets go through without hitting any metal. Both guns shoot better with match grade ammo, but still are not what I consider to be target guns.
The M4-22 magazines are a bit better engineered and don't cost much more than the 1522 mags. That being said, the 1522 magazines drop free with a push of the mag release button and the M4-22 needs a slight pull to get the mag free from from the receiver. 1522 magazines can be used in the M4-22, but not vice-versa. The 1522 mags will drop free when used in the M4-22.
The 1522 frame is polymer; the M4-22 frame is aluminum.
Which would I recommend? Both. I don't think there is a bad choice between the two. I will recommend that you get a trigger upgrade for either/both. I have CMC 3.5lb single stage triggers in both and I can honestly say I think I shoot both of them more accurately than I did with factory triggers.