Hey!
As already pointed out, Meguiar's #26 is a pure wax in that it contains no cleaners and is meant for an already cleaned/polished surface.
Meguiar's Gold Class will provide a deeper and darker shine IMHO than #26. It also contains a polymer which means that it needs to be applied differently than the #26. Moreover, as someone already said, it does have very MILD cleaners that are more for assisting the bonding process rather than cleaing the paint like a typical and dedicated cleaner wax.
In terms of durability, that is a tough call. A beading surface is not an indicator that the wax has been eroded away. I find that with GC that after a wash or two, the beading decreases dramatically. But as I said that does not mean the wax is now gone. I would still give the edge to the #26 for durability overall.
I personally prefer #26 over the Gold Class. But for darker paints, GC is very hard to beat!
Tim