Maybe it because I like Glocks. But a 3rd Generation Glock 19 would be a very good choice.
No break in period needed. Have a good record for reliability too. Glock mags are reasonably priced. Lot's of aftermarket parts and accesories are available for them.
I recall reading in a gun mag of a trainer. And he said students that had very little experience, performed the best with Glocks over other handguns that were also offered.