I second the recommendation on SIG, I have built the 4*60 and are currently building the SSE, both are super easy to assemble and the quality of the kit is outstanding.
I have a GreatPlanes kit as well, but it's not as well cut and there's more to do with it.
Not necesserly harder to biuild, but it's not the same jig saw puzzle as the SIG kits are.

What level are you "flight wise"?
If you're a beginner I would recommend the SIG LT40, if you can fly already and want an easy to build sport plane the SIG SSE or 4*40 would be a good choice.