Of course, as you're probably already aware, JSGME is the first "mod" to install... After that, it's basically a matter of taste. Do you care if the game gets much more difficult to stay alive in while you play, if the difficulty level comes as part of the "environment" mod?
As you probably already know, there are all sorts of little mods for just one aspect of an environment, and full-blown "everything" environment mods. I wasn't much into what things looked like myself, until the recent past when I've gotten myself some stronger computer gear that can actually run some of the mods without hiccups. What I was playing regularly, prior to getting involved in the
FotRS Ultimate project (long post) is
Webster's Game Fixes Only v1.1, and added in the
Real Environment #1 Patch after installing it (
Real Environment SH4, which is multiple "#" folders - do the ReadMe!). Be sure and read all the ReadMe files, else you might end up with mod soup... Webster includes quite a few smaller mods in his GFO mod, and you have to be careful what, if anything, you put on top of it. It's doesn't pretty-up all aspects of the game, but I sure enjoy it's blend of changes. When "Fall of the Rising Sun, Ultimate" comes out though, with all it's proposed user-definable aspects, it may well supplant my current favorite. Then again, there are certain aspects of Webster's GFO that I do not want to lose, and I may end up with both of them side-by-side with MultiSH in control...