My gliders and I are a fan of the Silent Runner Wheel (I do not know if Exotic Nutrition is the only maker/seller of that or not but it is where I got mine).
Personally the config I like is the wide autoclean track with the cage attachment. Needless to say they always prefer the wheel that is higher in the cage than the lower ones.
The pros: no middle bar, attaches to the side of the cage, the wide track gives a little extra room for leap-frogging gliders, the "autoclean" does not catch their toes nor does it allow waste to collect in the wheel*
The cons: it is more expensive than the other wheels. The wide track, autoclean, and cage attachment are sold separately (though there are some bundles with these options), it can at times take 2 people to attach the wheel to the cage depending on cage, location, human arm wingspan, and the "autoclean" needs to be cleaned as frequently as any other track BUT at least it does let some waste drop which makes it not as bad as a regular track. That said, keep on your usual cleaning schedule with it despite the misnomer.
Their color options are neither here nor there. The glow-in-the-dark wheel cover is a little cool but it is not like it will offer much glow as you can imagine.