I’ll sign off on the lever belt for strongman as well.
I’d also consider a rehband strongman soft belt. I use that on at least as many events as my leather belt. I won’t say it’s as important as a leather belt. It’s not. But it has a ton of value, so if you can afford both, get both. I use the soft belt by itself on front carries, stones, and other miscellaneous events. I use it under my leather belt on log and axle clean and press.
as far as leather belts go, like I said, I like the lever, but there’s nothing wrong with the single prong. I use a lever now, but used single prong for a long time with no issue. 10mm is sufficient, 13mm isn’t needed for most people.