If Glocks fit your hands, a G35 tuned up a bit will do nicely (says the guy who does not like them). I love working on them, don't like shooting them. Granted a limited gun can be 'grip enhanced' so it wouldn't be so bad.
M&P's have a much better trigger and (for me) better ergo's. Comparing a tuned M&P trigger with a tuned Glock trigger, both at 2#'s, the M&P is still better for me. Shorter reset, crisper break. Just start with an "L" or Pro.
Parts are plenty for both. Both cost about the same. Both would benefit from sights and trigger work. Both can be stippled to achieve a great grip. I would go M&P, add Tungsten guide rod with 13# spring, and sights first. Then add trigger job, stipple and magwell in that order.