This. I don't have experience with Forms, but Rider is a massive improvement over VS on both platforms for "native" Xamarin development. I actually quite liked VS for Windows when I started working with it a couple of years ago, but as of late it seems to have gotten only slower and buggier. Since we do only Android / iOS at my job I don't even bother with Windows anymore. I still "need" VS for Mac to (a) build iOS layouts in interface designer (which is hell, I regularly consider going code only for those) and (b) to deploy Android apps when debugging. Rider will do that, but it doesn't do the fast assembly deployment that VS does so it's very slow even if there are no changes. And thus I write code in Rider, and run through VS. VS for Mac doesn't include as much bloat as VS for Windows, which makes it "better" because it's relatively light and doesn't lock up too long when switching to it. As an editor it's just annoying though. Debugging in it is a necessary pain right now.
If this sounds cumbersome... it is. I find it workable right now but I'm regularly annoyed. Build + deploys fail when I fire them off too soon after changing an .axml file. Builds fail as a rule, not an exception, when there are Xamarin or Android SDK updates. iOS is actually mostly fine, except for the hell that is the designer. All in all none of these things are show stoppers, but I don't think I could wholeheartedly recommend Xamarin for new apps.