I've built all of them except the Sig Fun Fly, but I have flown them all.

The Skybolt requires quite a bit of building and it always seems to come out tail heavy. No matter what I do. It will be marginally powered with any .60

The Goldberg Ultimate bipe requires less building, but still more than the last two. A good .60 will fly it fine.

The Something extra is easy to build, and fly. The .60 would be way too much for it. It has a VERY wide flight envelope.

The Fun Fly does not like to land and stay off it's nose, but it flys ok. But just ok.

Of them all, my choice would be between the Something Extra if your in a hurry, or the Ultimate if your patient. Both have strong high points. You could always look into the 40 size Ultimate ARF that Hobby People sells (hobbypeople.com). It's easy to assemble, inexpensive, and flys well. It's designed for a .46, but it works better with a .60 on the vertical performance. Goldberg also markets (through Great Pains) a 60 size Ultimate ARF. It's a little pricey, though.