I played Planescape Torment on Steam, and i have got to say, while the game is fantastic, I never really felt like i was faced with a challenge. Meamwhile both BG and BG2 can be brutal if you don't know what you are doing. There are a lot of enemies with resistance that you need to dispel etc.

planescape torment is practically a visual novel

baldur's gate is still pretty easy though.

Well, PS:T is story-focused, while BG 1-2-ToB is balancedly story AND battle focused (Icewind Dale being the other end of the spectrum being clearly battle-focused).

In PS:T you have almost no battles, and they are extremly clvl-adjusted.
The BG-series on the other hand solves problems with battle instead of witts. Your witts in BG come what quests to pick, which fights to choose.

It's been a long while since I've played PS:T too, but isn't it the case that, outside of certain specific foes/battles, you CAN'T die due to combat? If you die, you just sort of "revert to the nearest safe zone" and you can heal up and try again.

Yes, part of your character's story is that when he dies he will regenerate and awaken a few hours later. There are even a few quests and puzzles in the game that rely on this and you have to intentionally kill yourself progress.

PS:T beat me, easily, with too much wall of text. *shrug*