[account42]

For BG1 I suggest giving the original non-EE version a try without mods that move it BG2 engine (which the EE also does) and have a character focus on summons. It's sad to see the version most new players will experience has spell casting rules significantly different from what the game was originally designed with.

Also some more worthwhile ones:

  Infinity engine games (i.e. Baldur's Gate engine):
   Planescape: Torment (if you like the story aspect, combat is less engaging in this one but not as bad as some die hards will claim; skip the newer Torment form inXile)
   Icewind Dale I and II
  
  Arcanum
  
  ATOM RPG
  
  Wasteland 2 and 3
  
  More that I liked but will be a matter of taste:
   Shadowrun Returns and sequels
   Neverwinter Nights (early 3D graphics that are nothing to write home about unfortunate design consequences from supporting multiplayer, but has many worthwhile fan modules)

Also the early Fallouts of course like a sibling comment already suggested.