Coil springs offer more flex, and a nicer street ride. They aren't as stable as leafs, but it's a matter of preference. The interior is nice as well. I like my YJ's interior, but the TJ is a lot more modern. We've got a TJ in the family, and I own a YJ. I've driven the TJ a lot, and I really enjoy it. It's a little bouncy if you ask me, but I still like it.
Also, if you're serious about trail riding buy something with the D44. It's not the greatest of axles, but it's going to save you in the long run. Some Sports, all rubicons, and I believe all LJs came with a D44. It's capable of running up to a 35 locked.
Out of curiosity, what's wrong with your YJ?