Nice tabs, man!

I feel like Burning Wheel fits your criteria. Sure, there’s nothing but BWG in print right now, but for a while there you had BWR, MonBu, AdBu, MagBu, and all the peripheral supplements like Blossoms and Jihad. MonBu and MagBu are fun to thumb through.

But, yeah. As much as people make fun of GURPS or HERO for having a splat for just about everything, I can tell you that during my HERO days, there was something really enjoyable about getting a new, phat, sourcebook every month that essentially reinforced my fandom for the game; I’d get to read about a given topic and see it implemented in the system.

Geez, what a 180°. I am indie fanboy waxing nostalgic about splats. What the hell is wrong with me?