Yeah, I'd say you should go for Worldcraft 1.6. I've made most of my speedmaps in Valve Hammer Editor, which is a later version of Worldcraft, basically. Hammer is better but it needs some fiddling to get running with Quake maps.
So I'd recommend WC 1.6 for getting started the fastest, but if you want a more modern editor, you should get Valve Hammer from here:
Heres some longwinded advice to getting it working:
you need to get Qonverge, a utility set from Riot:
you need you run the 'wadconv.exe' program on your textures from the command line like "wadconv -wad2hl idbase" to input a wad called idbase.wad and export a half-life format wad called idbase.hlwad in the same directory. This is because hammer is for editing Half Life. You might have to rename your idbase.hlwad file to SOMETHING.wad so it shows up when you browse for textures to add new Wads.
You also need to get a Quake.fgd file from somewhere. The one in your worldcraft 1.6 folder will do fine. You choose it in the game profile page that pops up when you first start Hammer.