Depends on what I'm going for. I definitely don't ever use a bitter American IPA, I don't like that flavor in beer by itself, and I don't want it in my chili.
But don't be afraid to go with something dark and malty, the entire point is to build up the depth of the flavor profile. There are plenty of chili recipes that call for things like cinnamon, allspice, cloves-- I don't typically include those, but I will definitely use some of the winter/Christmas beers with those spices in them when making chili. So my batches around the holidays usually have something like that in them, but later in the winter season I typically go with lagers, with Czech pilsners being the most common.