At the time I had a Spec Rockhopper, did nothing but adjust the saddle height in 3 years. I was back on it 8 weeks after the surgery, going head first over the bars
11 year gap, and I bought a Cannondale Synapse, which I found too much of a stretch even with shorter stems (in all honesty, it was probably a size too big). I swapped that for a CAADX, but couldn't get comfortable on that either.
Last year, I bought a Genesis Longitude. Bars were swapped for some Jones Loop bars, which needed a little tweaking on the stem clamp to get the most comfortable position, to be honest, They were more for my wrists than anything else
I'm more upright and slower, but never been more comfortable on a bike. I get some stiffness if I stay in one position too long, but that happens with anything not just riding.
I get some crunching and cracking when stretching my neck, but that's been like that as long as I can remember - I was told that the discs either side of the fusion had some wear and tear
Just to add, I had the surgery at 32, I'm 54 now, so not much younger than you. If I needed it again, I wouldn't hesitate