Pt 22,or Titan 25 acp for summer shorts t shirt,winter or any additional clothing a llama 32 acp,as to what will hide on you as an individual depends a lot on your build,frame ,height and mostly weight.A large man can hide a cannon,small one pea shooters.
Small plastic sub compacts are nice to carry,hard to use and shoot again,virtually useless at any distance and frequently crack frames due to hi pressure defense loads they were not meant to shoot.
Steel and weight mean less recoil,smaller caliber in same means less weight.My 32 acp llama 3.6 barrel especial shooting sellier and belliot 60 grain jhp,1200 fps ,205 fpe rated that out of a ppk 3.2 barrel,is equal to most sub compact 380 shooting what its rated for ie cup pressure or fpe rating. Or an average snubby shooting non plus p 38.
Go with what you are comfortable with as its you the user and or carrier.