I am effectively running now three campaigns in different systems

Nice. My friends and I are in the third year of our Enemy Within campaign, and we're still on the first book.

Ran a 2.5 year campaign in this setting. Had enormous amounts of fun with it, and it remains one of my very favorite settings to this day.

They have a new version? I remember playing this back in the 90s. The unconventional classes and progression system were neat, but I usually just ended up playing the suicidal dwarf. Troll slayer I think?
- It was huge in the 90's with the everything you need in one book, while AD&D collections of book were too expensive for the broke kids we were.
  I believe they're know at the 4th edition, and unfortunately switched to multiple books like many others publishers
- I met my spouse in a 2003 campaign and he had also taken a Dwarf and became a troll-slayer. I started out aiming for a magic user of some kind and ended up as a soothsayer and fortune teller. That games' character building and progression was wild. I think we played a demo of the 2nd Ed rules at our local game shop a few years later.

How did it go?
My friend and I were interested a few years ago and took a look at the manual, and our head was spinning while reading the countless tables referencing other tables. I remember everything feeling twice as convoluted as how it should've been, for no reason.
- Or you can just skip most of the tables for your first campaign and just add the ones you want to at the moment you want to add them.
  The actual game rules are surprisingly simple once you figure out the basics. At least that was my exerience during a 1 year campaign. We only added the critical hit tables like 3/4 in and they're by far the most iconic thing about WFRP.

So, OP what are you playing. Enemy Within, a custom campaign ore something completely different?
- A campaign from old magazine in my country about exploration in Araby down south from the Empire, but for first session I did a trial run, where I put them against a Harpy and some undead, they did more than fine.