TLDR: what's your favorite tabletop system (mechanics only! not about the setting!) and why?

Longer complicated question: I've never played tabletop or pen-and-paper-and-dice RPGs much, so I'm not very familiar with how many there are that are distinctly different from each other, not mostly-clones. I was contemplating that shelf in the bookstore's games section the other day though, thinking I really should do a little research to get myself familiar with the variety of tabletop gaming systems, especially things that are quite different from the old few tabletop systems that RPG video game systems were originally based on. I want to get familiar with innovations in tabletop land in the past 15 years. So, anyone want to recommend a unique system or new development within a system for me to look at?

I am not too crazy on tabletop games. But here are some of the classics that I like and some people also like:

The Settlers

Agricola

Dominion

Munchkin

I am not too crazy on tabletop games. But here are some of the classics that I like and some people also like:

The Settlers

Agricola

Dominion

Munchkin

Oh, I was talking about the kind of roleplaying games where there's a GM and the other players create characters according to a book, plus there are modules for extra resource material, then the group meets once or twice a week as long as the campaign lasts. D&D, GURPS, etc. Though, I've played 3 of those 4 board games/card games and I agree that they are interesting and worth looking at. Pretty sure I've played over 100 games of Settlers alone...