Suburban roof racks - got any advice?

[Electricduane]

Been thinking about getting a roof rack, was hoping some of you would have some input.

I see one made by Smittybuilt, one by ARB, and one called a "Defender." Some are bolt-together and some are welded, 1-piece units.

Some basic questions:

Which one/brand is best?
I assume they all attach by drilling through the roof?
Easy to install?
How much weight can they handle?
OK to put the spare up there?
How many inches of height do they add overall?
Any other issues/concerns/advice?

Thanks!