I really have no idea how MLS stacks up to 2nd division leagues, other than clearly being behind The Championship. The issues with MLS relate to depth, and that comes from the salary cap and the limit on foreign players. Was the Revs team of two years ago good? Sure, they found Turner out of nowhere, they had young Canadian Buchanan, Polish striker Buksa and a quality Spanish mid in Gil. But MLS doesn't allow you to keep that intact. Turner, Buchanan and Buksa are all gone, each at over $6M transfer fee. They may have found another gem keeper in Petrovic.
The Transfer market/value is probably a good way to evaluate the leagues. The issue with the MLS is that it isn't supposed to be a developmental league, like some of the lower division European leagues.
This overview shows all transfers of the Major League Soccer in the season 2023. The clubs are ordered by their final position of the previous season.
www.transfermarkt.us