Instead of tomato puree
Not sure what other ingredients you have in the pot. But if you have all the flavor you need in there and are just concerned about consistency (since you mentioned runny chili), you can do two things. 1) reduce the liquid by cooking it down on a higher heat until the water steams off and the flavors conentrate, and/or 2) add a slurry mixture to thicken it up (corn starch dissolved in water is the most common).
I would puree the tomatoes if you want a smoother tomato background or cut with scissors in the can for chunky. Adding cornmeal or polenta, either will work, gives chili a nice richness, and will thicken it. I don't use puree for chili myself, just whole canned or fresh tomatoes. But if you want it nice and thick, another thing is you can mash some of the beans, that thickens it too without adding another starch.
Some chili is made without tomato products using chili powder only.