Which of the Disgaea games on Switch is considered the Best One?
As they're all on sale, and there are times when "grindy JRPG" feels right, y'know?
I am depressingly well situated to answer this as I recently found myself a little Disgaea-curious and grabbed a bundle of like all of them:
1- It's a little, you know, ANIME, but mostly keeps it in check. Has that really good numbers-go-upness, a surprisingly good dub, and when what passes for the plot starts flagging in the back half we bring in these 30s sci-fi serial dorks out of nowhere and just let the game be about them now, so that's great. Probably still the best in the series. Also the one you've definitely played already.
2- Basically the same game as 1 mechanically. There's like, 1 new class? Item world pirates are now a thing and I mean that's just delightful? Plot is... less than memorable but I don't recall ever being offended. Etna shows up and is upset about not having a 4 digit level I remember.
3-This one is freaking garbage. The whole use-this-weapon-type-to-learn-new-skills system is out somehow, and instead you buy all skills by spending way too much mana, which you don't have access to and there's no good grind spots until like, the end of the game, so get used to everyone just generically attacking. Lot of other weird little changes for changes sake I'm not a fan of. So many long tedious puzzle battles you can't just plow through by being level 5000. There's this weird classroom seating chart system that gives minor bonuses but also requires you to be transphobic to a power ranger to progress. The plot has this "it's an evil school so to get good grades you need to cut classes and never study" thing which is charming for like, 5 minutes then gets old. Someone really thought having Emeril Lagasse as an inspirational NPC was the funniest thing ever, and the protagonist is voiced by an infamous pedophile which kinda tarnishes the experience a fair bit!
4- I honestly skipped 4 (at least for now) because it maintains all the mechanical changes from 3 and I hate like all of those.
D2- This one was explicitly made for people who hated the changes made in 3 and 4 and the shift into really saccarine plots that 2 got rolling. So it basically resets to how 1 worked except I'm pretty sure item world pirates are still a thing because why change that, there's a couple new/kept-from-sequels classes, and some nice little quality of life tweaks like if you want to change your spear girl into a higher tier of spear girl you can just do that directly without reincarnating and resetting her level and palettes aren't strictly tied to class tier so you can keep looks you like. And then the plot's just the original game's cast having more inconsequential adventures. Also I believe it gets around the standard plot runs out of steam problem by just having less plot generally.
5- ... I know nothing about 5 at all except that it was made after D2 but I think it sticks with the mechanical tweaks from 3 and 4 which, again, are bad.
So tl;dr 1 2 or D2 I guess.