I have owned my tj for about 2.5 yrs and purchased a 04 grand Cherokee limited with the v8 for my son about 2 months ago and drove it enough before handing it over to give you an opinion.
I really love them both. But for different reasons. The GC is more luxury and what comes with that is more electronics, and things to go wrong. We must have chased 8 different gremlins before handing it over. And the abs light is still on and the left blinker doesn’t work when it’s cold. It was owned previously by a mechanic and has 226,000 miles and runs great. And is comfortable but would not classify it as fun. Just a nice ride.
My tj on the other hand is just plain fun. Reliable, easy to work on, and a classic vehicle I feel.
My vote is to watch for a great deal on a grand Cherokee , and keep your tj for fun. I got the Gc for 1,500. I feel that was a great deal. But a gamble especially now seeing all the little things that seem to get glitchy after time goes on.
Go on a different jeep forum under grand cherokees and read some of the threads. You will get a feel for the sorts of things you might be dealing with.
Good luck!