The best action games like MadWorld are Anarchy Reigns, Metal Gear Rising: Revengeance and The Wonderful 101. Below are 9, each with the reason it is here — and, at the end, what filtering to action costs you.
Filtering to action means you want the fighting to carry the game rather than the story or the map. It is the right filter when what you actually miss is how something felt in your hands.
What you get: Combat you get better at. Action games put their design budget into the moment-to-moment, so the thing you are doing in minute two is the thing you are still doing in hour twenty, only better.
What made MadWorld worth playing in the first place is covered on the full list. This page is the action part of that answer, and only the action part.
The direct sequel in all but name, by the same studio.
Platinum again, and built around one very good idea.
Kamiya at his strangest, and the most mechanically dense Platinum game.
The other great stylised Wii action game, and just as odd.
Platinum's combat at full depth.
The genre's origin, and the style meter came from here.
For the commitment to one visual conceit above all else.
Scoring style over efficiency, in two dimensions.
Platinum's most recent original, and the best-produced.
Pacing and world. Action games rarely have the quiet stretches or the writing that the adventure and RPG picks bring, and a few of them are shorter than they look.
The full list is on games like MadWorld — 9 picks, no genre filter.
Anarchy Reigns. The direct sequel in all but name, by the same studio.
No. MadWorld released on the Nintendo Wii, but a recommendation is only useful if you can play it, so the picks above span platforms and eras. What they share is the genre and the reason.
A small set of verbs and a game that keeps finding new questions to ask of them. The weak ones add buttons instead; the strong ones make you better at the ones you already have.
No, and difficulty is a poor proxy for depth. Some of the hardest action games have very few decisions in them, and some of the deepest have a difficulty setting that lets you meet them halfway.
By hand. Each pick was written for the full MadWorld list first, on what the game actually does, and this page is the part of that list that is action — never a genre tag lookup, which is how "best racing games like Super Mario 64" used to be a page on this site.
Or read the action guide for where to start in the genre generally.