Top 10 Pyramid!!!

[Pseudonym]

I've not bought many (only 5, actually) but:
I like 3/77 Combat for it's overall utility, fighting giant enemies is cool, and I have heavily integrated CER into my Dungeon Fantasy games.
I like 3/66 Laws of Magic because of the interesting alternatives for the RPM magic system.

4th Edition festival (3/70) as mentioned earlier is a nice quick reference for content that already exists elsewhere. It wasn't especially helpful *to me* but I'd recommend it as a good "starter pack supplement" for someone interested in exploring what directions they can take GURPS in.

Social Engineering (3/54), in theory, I like it, but honestly haven't had a chance to play a campaign with intensive social intrigue, so even though I have most of the Social Engineering line, I got nothing to do with them. :F

I got Weird Science (3/46) because I wanted a crafting system and was turned on to Metatronic Generators. It does what it is supposed to do, but frankly, I now prefer the Sorcery version of the crafting system because it mostly covers what Metatronic Generators covers, but feels more flexible, my sticking point being, I don't know the fair cost of making a metatronic generator that uses a different skill that may be easier or harder.

Thinking about picking up some more issues in the "pointless" series, and/or the alternate GURPS series, because I personally like having tons of choices for alternate mechanics and being able to say, "this is the exact crafting/skill development/resolution/magic system for the feeling I'm trying to invoke in my campaign."

So, hopefully without hijacking the point of this thread too much, any recommendations for someone who likes leisurely perusing alternate mechanics? Specifically, I like stuff usually in the vein of Low Tech, Fantasy, and Dungeon Fantasy, and I'm thinking that the Alternate GURPS, and pointless x-ing and y-ing lines fetch my attention. Any must-haves or killer apps in those directions?