Depends on your budget, family members, care style, cooking style, and a whole host of other factors. Sometimes multiple materials is the best choice.

All stone will chip in the right circumstances, man made stone included. Concrete is alos porous, and etches, and needs to be kept sealed. Stainless is a great choice if the kitchen design supports it, but you have to be OK with the patina that will develop. There are plusses and minuses to every material and you have to accept the minuses as part of the deal in any marriage.

The cabinets underneath need to justify the expense of an expensive countertop that won't get moved again. If they are old, or lack drawers, or have exposed hinges and poor hardware, or are even new builder grade chinesecrapola, you'd be better off getting new cabinets before you think about counters. Don't make the mistake of thinking that you can change anything once you enter into this marriage. Divorcing the cabinets ain't gonna happen. Make sure you have a solid foundation for the future first.