I agree that an LCP of whichever generation will conceal as good as or better than anything else.
I also have an LC9 in a crossbreed IWB that won't be seen until it is too late.
With the right holster a S&W 442/642/638 etc. will carry well in a large enough front pocket and be very comfortable, easy to draw and hard to see for anyone who doesn't know you have it.
You're probably going to have to play the gun/ holster game until you find what works for you.
Just remember, nobody will be looking at your waistband or pockets as critically as you will.