In general, the acid in the tomato will cut the richness of the beef. Whether you use paste, sauce, stewed tomatoes or even juice is totally your call. Keep an eye on the proportions and you should be fine.
I usually use tomato paste in beef stew, or plain diced tomatoes. If you're looking for richer undertones, I can suggest a hit of molasses if it's available..if you're looking to brighten it a bit, a splash of red wine vinegar should do the trick.