Unless I'm with my daughter I greatly prefer to solo dive for a number of reasons.
1) I can take my time and peer in to every little crevice without having to worry if my insta-buddy is dead on the sea floor, a mile ahead of me cause they're frickin aquaman and don't care about the sites, etc
2) I didn't pay a couple grand for that once every two years if i'm lucky vacation to be a babysitter. I'm there to dive, dive, dive. Not watch some insta-moron flail around, or share my air because someone has no control
True story. My very first dive vacation was to Bonaire back in..96 i think. I went with the LDS but was alone. I got paired with a somewhat nice overweight lady. IIRC..she was only OW certified whereas i had gotten up to rescue at that point and was working on my Masters.
Our first dive after the checkout dive we got down to like..IDK, 30 feet. She had some kinda problem with air, or BC or something and shot to the surface. I was about ten feet below her and tried to grab her fin to steady her so i could get to her to see what was up. All that did was pull me up with her. I let go and made a slow ascent after her.
When I asked what was up, she said she couldnt equalize. Rather than just go up a few feet and try again, she shot up to the surface. We did a slow descent, she took her time clearing, and we finished the dive. We did several more dives off of Sand Dollar in the shallows (no more than 50 feet or so).
We had an arrangement to meet every morning for breakfast and then go diving. I waited for like an hour one morning and decided to check on her only to discover she had fallen down the steps from the second floor of the hotel. She didn't break anything thankfully, but that pretty much killed her diving. I continued to do boat dives and tagged along with a couple other people for some shore dives. But this experience has soured me on the insta-buddy bit.
When i do solo, i try and stay under 50 feet or so. That's my max, but depending on the location its usually lower. Peal Lake near me for instance, everything worth seeing is below 40 feet anyway.
When I did my DM internship at my LDS i would drive ahead of the group to Devils Lake so i could grab the good parking spots, and tie off the flag on the training platform. I would do a ten minute solo dive after tying off to just relax and be at peace before the noobs showed up.
Solo diving is Quiet..its Peaceful, Its relaxing, and as long as you know what your doing, IMO..its the best way to go. Provided you aren't being stupid and doing solo cave diving, or penetration wreck dives, or dives below 60 feet without at a minimum a pony bottle. And redundant everything of course.