So much choice these days, compared to 15 years ago. Most modern stuff is pretty light and strong so the days of 40lb street bikes are thankfully gone. Assuming you aren't gonna ride flatland (too many hours on the bike needed), then as said above, 20/20.5 inch tt for tech street/park or if you are short, and 21/21+ for trails/park. 1/2 inch on bmx frames makes a much bigger difference than on mtb.
I currently ride a 21.75 tt brew race frame, but if you want to run pegs, then probably best to avoid race bikes as the dropouts aren't really up to the abuse – a steel one should be fine for trails/dj though unless you are particularly heavy handed.
I've got a 21 inch tt S&M next gen Holmes frame sat in the van doing nothing if you want something strong and not especially light for a small fee.