To me there's kinda 2 "phases" of R.E.M.
The early years (I would say first 5 albums or so) have that jangle pop feel with the guitars being a shining force. Songs like "Can't Get There From Here" and "Green Grow the Rushes" from Fables, or "Radio Free Europe" from Murmur, or "Harborcoat" from Reckoning are a few examples of this. It's a huge reason why I like these albums so much, the guitars just pull you in and while they are not on the heavier side of the rock swamp, the songs really groove. For me Fables is the best from this period but Murmur, Life's Rich Pageant, Reckoning and Document are all great too for sure.
Then I would say they had a bit of a Radiohead-mellowing out and expanding their ideas. Sometimes with great results, sometimes maybe not, but at least they're taking chances. Songs like "Daysleeper" or "Everybody Hurts" feel so distant from what the band did on the earlier albums, yet it's still just as good but in different ways. I think the band matured and while I think they got more inconsistent, they were able to write songs that they weren't capable of writing in their more rocking phase IMO. Every time I listen to Automatic For the People I always get reminded of the fact that most of that album consists of calm songs, which would normally bother me (because a balance is nice) but it works really well. "Ignoreland" is a personal favorite that gets overshadowed by the bigger hits of the album.