I too have the good fortune of having both a new Jeep — mine is a 2019 JLUR that is almost fully optioned --and my new-to-me 2003 TJ.
I really, really enjoy my JLUR and it serves duty in my family as my DD, a grocery-getter, a secondary kid-hauler, and a weekend adventure rig that's laughs at the mundane things our family has asked it to do. I plan to keep it until the wheels fall off, or rather, until the electronics give out because we all know the Achilles heel of these newer Jeeps tends to be that. I've learned to perform basic vehicle maintenance on my JL and I've really enjoyed that aspect of owning it but there's only so many bolts to check and fittings to grease on a new Jeep...
And of course now that I have 3 months worth of blood, sweat and tears into my TJ build it's quite clear to my family and friends that I'm a complete goner. That is to say, while I really, really, adore my JLUR, I am absolutely head-over-heels, can't stop thinking about her, staring at her from across a crowded parking lot, waking up in the middle of the night in a cold sweat in love with my 2003 TJ. It's the Jeep I always wanted not only for its aesthetic but for the fact that it offers a driving experience unlike any other vehicle. Rowing gears down a backroad in the 4.0 with the top down and the half doors on is for me just pure heaven. While it may not be as easy to DD as a JL/JLU what it offers in terms of pure fun simply cannot be discounted.
If I can in anyway help it, I'll never be without a TJ.