I dunno, personally, I loved the last 2 albums. Super Collider almost had a bit of a Motorhead-like vibe to it, which I think was partially because of Mustaine's vocals on it. But the riffs were all memorable and it just had a solid Heavy Metal sound to it. It wasn't very thrashy, but like I said, that's not why I like Megadeth anyway.
And 13 I thought was absolutely amazing. Of course, it almost felt like a compilation album, with songs they've done for video games, and old ideas finally being developed. But that's what I like about it, there's a lot of variety there. It's just satisfying to listen to.
But hey, Megadeth is the one band that actually has just enough variety to split the fans a little bit, so that's probably not a bad thing. It's just a shame that people hate on the last 2 albums so much.