Flat heels are essential for proper rise and fall in Foxtrot, Waltzes, Quickstep , etc. imo

For a first pair of shoes, Leads should get Standard/Smooth, and Follows should get Latin.

For leads, a latin heel *will* eventually make a difference in your ability to engage and emphasize your hip, but you will struggle to even learn proper technique if you try do Standard/Smooth dances with a Latin heel.

For follows, my information, admittedly second hand, is that the effect is less pronounced. You will, however, eventually benefit from Standard/Smooth shoes, particularly in Foxtrot, where heels are dragged quite a bit.