In my opinion, Matrix AntiCheat. It’s free, effective, and highly configurable. I’ve tested it myself, and its default configuration is actually great, too.
NoCheatPlus is always a solid option, especially for movement. I'd also take a look at Horizon's dev builds from their discord if you want another option. Quite a few false positives and would require some fine tuning at its current state but detects most cheats well. I shared my config on there a while ago but it'll require a bit of searching.
horizons; was the issue with keep alive packets fixed? It was causing all my players to be continuously d/c'ed and i ultimately had to stop using it and report the issue. havent check
I gave up on Matrix. Too many false positives, plus no way to disable individual checks in certain worlds.
