I’ve been using backloggery.com for more than 15 years.
It’s a simple, manual site, but I think that’s also its main strenght - I’ve had too many issues with other sites where I wanted to add a niche game I played but it was not in their databases, inconsistent naming between games in the same series, no ability to add duplicates when I occasionally double-diped on a game and so on.
It has all features I need - you can add reviews, notes, track priorities, wishlist, borrowed games, make custom lists, get stats… it’s also community supported with no ads.
The site was a bit stale without development for a while, but Drumble (the owner) finished a major rewrite last year and started developing new features again. You can check his profile here for an example.
There’s a lot of videos and articles like this one discussing how Stage 1-1 of Super Mario Bros for the NES is a cleverly designed tutorial for the core game mechanics.