Welcome to the community!
There's a bunch of old salts around here that will be glad to steer you in the right direction, and as for your question, I'll add my own two cents...
I played vanilla SHIII for a long time. It's quite the experience without mods, but the wide variety of options available only improve the game. I've personally always been a fan of GWX, which, while not as realistic as, say, NYGM, or (by itself) not as pretty as LSHIII can be, is an outstanding supermod adding a lot of content in its own right.
Pick and choose your own SHIII experience, and remember that the old breed of Kaleuns are always willing to help! Good hunting!