PDF Recommendations

[Sangtraït]

I've been away from GURPS for some years ( I admit it, I'm a heretic) but now I have embraced this system more strongly than ever. I thought that the flame of GURPS was extinguishing because there aren't in my FLGS any new manuals, but going to the website of Steve Jackson Games, Warehouse 23 and on the forums I have found a mine of supplements in PDF format. Right now I am overwhelmed by the wide range of supplements for GURPS 4th Edition.

And my question is, and I know it is very generic, but I want to know the opinions of GURPS fans: Of all the supplements that exists in PDF for GURPS 4th Edition, which one do you recommend me due to their quality? Mainly for fantasy and / or science fiction campaigns.

Thank you!