I had a ride in a sidecar once, it was neat , but weird. I understand driving a sidecar rig takes some learnig, but driving my trike only took learning to be confident that I couldn't tip it over! (You could say I tried to) it isn't your average trike, and I did have to learn to shift an H - pattern under my left thigh, but that was easy enough.
So my vote is trike, but then I'm biased and still have two-wheelers too.
I rode Goldwing side hack rig in the early ‘80s for a few years. Last fall acquired an identical Vetter Terraplane for my 10 year old new to me ‘83 Interstate. Last year saw myself needing to move to three wheels. Nine hundred pound bike was just getting too heavy. Liked the trikes, but having hack experience and no funds for trike or Spider made adding car to my great running Wing an easy decision. Cool factor was definitely on top of my list. Lots of shoulder work to drive the rig, but a lot of fun slower speed touring.
My biggest take away between bike and rig. It’s not a motorcycle anymore. It’s a 70 mph tractor!!
If I had to choose it would be a modern Morgan see pic. A sports car shop I worked at had an original Morgan restored by the resident long beard Harley expert guy, it was cool and rare but required fabrication of the flywheel to crankshaft interface to a toothed arrangement on that old motor. The original just had a cotter key that easily failed.