Gothic 1 and 2 were great, imo better than any TES.
You have to work your way up from the bottom and if you enter the wrong cave/valley too early, or piss off the wrong npc too early, you are going to get raped.
Gothic 3 is the biggest Gothic, only good with the fan patches which fix its issues/bugs.
Gothic 4 Arcania is a turd, avoid at all cost.
Risen 1 is a low budget Gothic 1, no more no less.
Risen 2 sucks, a shitty pirate game in which you don't control ships ever (at least as far as i went before quitting).
Never played 3.
Elex is the last of the Gothic clones, the exploration is good, the combat is bad, the plot is generic.
The interesting thing about it is that, depending of the faction you side with, you will have a character that looks and plays like either a Mass Effect character, a Fallout character or a Skyrim character