The greengrocers divide potatoes into 2 sorts, floury and waxy.
The ones I think have the best flavour - Sharpes Express (early) and King Edward (maincrop) are floury. Sharpes boil OK when really small, but as they get bigger, if you boil them the outer layer separates from the inside, and they go to a soupy mush.
So I always steam both sorts.
If I want to flavour them with mint I boil them with mint for a few minutes and finish them in the steamer.