How often are you guys changing out sets? I'd imagine it depends on how often you're skating and preferences but to put it in perspective:
I got my first pair of F4's (og classics) in October, and they are down to a 53mm from 56mm when I bought them. I love them, I'm excited to maybe try a different shape, and possibly a 97a from the 99a I currently ride. However, my buddy thinks I'm fiending too hard haha.
So you are going through roughly a mm a month, which is not uncommon - really just depends on how much sideways action the wheels get, or how much you have to slide, carve in and out or turn at the end of whatever it is you are skating, eg a fairly rough carpark or old concrete that you have to slide to stop or similar can eat through wheels very quickly, maybe more quickly than most other skating, vs skating a smooth new park which wheels last for a long, long time and barely wear down at all. Wheels on my ramp boards seem to never wear down in size at all, but park or all rounders, especially doing what I said above, I can go through that and more if I am really pushing it.
As to wheel shape, I also think it is relevant to consider how long you like your wheels to last, eg some people skate them down one or two mm and change them out, as they are used to a very specific size and shape, while others, self included, used to get wheels way too big, skate them down through good sizes until they were way too small, then start the process again. Having multiple setups kind of helped with that, big wheels on a "go fast" board, medium sized wheels on an "all rounder" and then smaller wheels on a "tech setup".
Some wheels will stay rounder for longer too, others will get really squared or sharp on the edges once they wear down a few mm, but again it comes down to how people skate - some are very particular about things like the wheel shape and edge of the wheels, others just skate whatever and do whatever works for them.
OG Classics you know already - maybe the thinnest wheel of your options, which also get a sharp edge once worn down a lot, but are lightest and give the most truck grinding room too.
Lock ins are now a bit wider for the relative diameter, but still come out as a medium wheel, maybe a good all rounder, with two options - a different shape on each side, so as some people do, you could run them in or out for a different feel of wheel there, but then some people don't like that they can't easily turn them around if they wear too much one way.
Radial Full are the widest and great for the size to roughness ratio, eg wider wheels handle rougher terrain way more easily, but they could be heavier and a wider wheel gives you less width to grind, especially on 149s or less.
97 over 99 is also a good option for really rough ground, give a little more grip and might make things easier on the vibrations, but they could also feel a little slower and sluggish at times, compared to the 99s too. Bigger softer wheels work well for me, if I need a bit more grip or just to take the edge off whatever surface I am riding on, so I like to have a set of Radial Full 97s around just in case, as well as my usual other Classic Full (or modified other shapes) in 99s.