I've had a TJ and now have a YJ. Had the TJ, had my twins, sold it for a car I could drive two kids AND stuff around in, and then picked up my current YJ about three years ago as a second vehicle. I'm partial to pros of both models, and from my experience:
Get a 4.0L HO motor. If a YJ, from '91 on, or if a TJ, just get the inline 6. My TJ was a 4 banger, and the YJ has more power and believe it or not is a little better on gas than the TJ was. If you get a YJ, consider looking for a '94 or '95. The '95 has superior rustproofing on the frame, and the '94 and '95 have an external clutch slave cylinder, which makes repairing the clutch master and slave a 4 bolt job. Older YJ's require dropping the trans to get to the slave. Also, older YJ's will have carburetors. Some love carbs, but personally I do like the convenience of fuel injection and for me it just shortens the list of repairs / maintenance.
The TJ is definitely "fancier". Digital stuff on the gauges, fancier panels on the interior. Easier (MUCH) to get to the speakers if you are into making your radio loud. However, the YJ has an elegant simplicity that I personally love. I have enough to do on the computer, smartphone, fancy devices and all that crap. It is, for me, great to step back in time to 1994 in my YJ, listen to the motor and ride around.
The YJ is leaf sprung, which is kind of cool I think. However, it's a bumpier ride than a TJ.
Finally, TJ's and YJ's alike can rust. Check for rust. Check for it on the frame, the floors, the rocker panels, near all the fender flares, check all over the place. Then check it again. Rust is a killer. I don't know where you live, but you should be able to identify around 3 to 5 Jeeps that fit your criteria to go look at. Check 'em all for rust three times each. Get on the ground. Crawl all up and down those things.
That's probably more than two cents, but hope it helps.
The choice is ultimately yours, so good luck and have fun!
