I would have to say to go with a Windham Weaponry SRC, or a DMPS rifle. The Windham is better than the new Bushmaster any day, and it has quite a few components better than the M&P sport. Upon speaking with a well known reviewer on Youtube (Military Arms Channel), the Windham SRC is almost identical to a Colt, which happens to be much more expensive.
It has a forward assist (M&P doesn't), a Chrome lined barrel (Bushy does too, but they are at least $300 more), and a well staked gas key.
MSRP is $1040 on the SRC, but I got mine for $770.