Depends on your budget. Granite for those who have the will to maintain them or man-made quartz for those who don't. They have roughly the same price tag (depending on what you choose). It also depends on cabinet colours, flooring colours, paint colour, and overall design style.

For example, blue slate/soap stone pair nicely with natural maple or cherry. Green slate/soap stone goes nicely with white cabs. Choosing a counter top is a "whole picture" kinda deal.

What do you have going, what are your expectations from stone and what is your budget? Do you have photos?