[exalted]

I used a lot of system first Drakar och Demoner the swedish grittier version of D&D, then GURPS (still the most influential on my campaigns), then Vampires, EON (another swedish rpg this one redicuslously detailed fantasy), then Hunters when that appeared several years later and then D&D 3.5, Exalted (no edition entirely playable as written), Pathfinder, Dark Heresy, L5R even tried a bit of FATE some years ago. I've read a lot of other systems as well but rarely found any reason to play them, even if I run a game in their settings.

The last well probably closer to a decade I've never use a system as written probably affected by the GURPS idea of using what is useful I'm likely to take a setting and then a system I think reflect that setting and adventure type. Then I tweak or even rewrite the system to fit the setting and my group, anything from a single page of houserules to a complete rewrite in pdf form. Identifying what your group likes is more important than trying out new systems that are very likely poor fits. My group isn't really interested in what system is used for example they want a lot of options, they want to be able to build their character over a long arc so systems with no real character development are out those with no real nuance like FATE are out. While combat is a large part of our campaigns there are frequently entire sessions where no one rolls for initiative so there needs to be some other things to focus on so straight up combat simulators like D&D are mostly out. Identify what your players like and what you like to run then build setting and rules around it or at least choose setting and rules that are conducive to that playstyle.

Current campaign is Star Wars using the last roll and keep edition of L5R for rules with extensive modifications to character options but really magic sword swinging samurai and sword swinging space wizards have a lot in common. :D

Before that it was a kind of expanded and partially simplified Pathfinder/3.5 running the Dark Sun universe.

Before that it was Exalted using a bit of exalted 2nd - 3rd ed mixed up with a lot of gurps.

In the end system rarely matters that much as long as everyone find the amount of moving parts sufficient/not too much, setting is the important part and good ones to raid are anything of a genre the players are likely to find interesting and it is immensly easier to run something that everyone has experience of or can relate to. Some really good RPG's to raid for setting for my group have been Exalted, Dark Sun, Star Wars, Warhammer (and the 40k variants) and Warcraft but I guess once more it depends on the group.