Well, this is the one my buddies and I passed around when we were younger. I am not sure how diffinitive it is. I also downloaded this one a few years ago and enjoyed it. This one appears to be $1 if you have a kindle. I think they are all original Robert E. Howard works. Expect excellently written combat, some racism and sexism, and overall just fun reading. Enjoy!

I recommend reading Howard's short stories first (the comics will spoil his original stories since they are often adaptations). Then start working through the classic The Savage Sword of Conan (1974) comics.

I bought The Complete Conan Saga a few years ago and loved it. The other two are cheaper and i would guess comparable.