Ditto as to what others have said about fabric, style, and texture being more important than number of buttons. And I add "color" as a factor too.
Solid color cashmere sportcoats usually work well, multicolored herringbone and tweed woven wool or wool blend coats are great. Generally, finer fabrics such as silk don't work *as well.* Therefore it is easier to put together a jeans and sportcoat combination with the heavier fall and winter style coats, however you can pull off wearing some textured linen-silk fabrics or even cotton seersucker.
Word of warning, is stay away at all cost from the bright summery solid color coats in: sky blue, lemon green, bright yellow, rosy pink, etc. They are best paired with white khakis and relegated to the pre-outing luncheon at the country club golf course.
I wear both two and three button style coats and find both work equally well.
All that said, I will confess that I have never purchased a sportcoat just to wear with jeans. Collected all of mine for creating (coat and tie combinations) to wear to work all week. I wind up wearing them with jeans (as many people would don a nylon windbreaker) in evenings or on weekends just to get some additional wear and use from them.