Bit late on the DMC talk but I'd say DMC5 is the best, followed by 3 which I still think is really solid. Still has great combat - laid the foundation and more for later DMCs and Platinum Games' titles, great sense of style and great characters/character arcs. I think DMC5 was right to abandon the metroidvania-like exploration elements in this game and earlier titles though, to focus on what the series is really good at. The platforming did go back to being about as bad as it used to be, but it's kind of endearing and doesn't detract from the good stuff.
Would normally say 4 comes after them but not so sure anymore. DmC has a lot more 'game' to it. 4 has even better combat than 3, like by another dimension if you're really mining for depth but there are few actual levels which are recycled for the latter half of the game and not in a very good way. The story felt similarly unfinished. Then Definitive Edtion fixes some of DmC's shortcomings whereas DMC5 makes 4 somewhat redundant because it offers most of what it does combat-wise and then some.
Also unsure about where I'd put DMC 1 because I also really like it and I think it's still worth going back to since it's a bit different from the others. Great atmosphere as a some-time Resi game, which in part is what makes the exploration shine more.
And then yeah, DMC 2 because it's just awful. Would also say it's one of the worst games I've played. Just so mind-numbingly boring.
As to why DMC was rebooted with DmC, it wasn't that people thought 4 was only okay, it was most likely because sales didn't meet expectations. It was the first title to go multi-plat but only sold a bit more than 3. Still decent sales, but yeah.