Quad Ring Composed of 4 Lobes, Great Resistance of Abrasion, Lower Coefficient Of Friction, Keeps the Pressure Even, More Efficient

What Makes Multiseal® Low Friction Seals and X-Ring Seals Better • A better seal – With their multi-lobed designs, they provide more sealing surfaces than standard O-Rings.
Increased life for the seal ring – With multiple seal points, less squeeze is required to provide an effective seal. This means less
friction and wear which will increase seal life and lower maintenance costs.
Prevents spiral failure – The square cross sections resist distortion called “spiral twist” that may be encountered when using O-Rings.
Puts parting lines where they belong – Unlike an O-Ring, where the parting line is found on the only sealing surface, the parting lines
of Multiseal® low friction seals and X-Ring compression seals are located in the center of the cross section away from the primary
sealing surfaces.
Better lubricant retention – The grooves on the inside and outside diameter of these rings retain lubricant thereby lowering friction and
extending packing life.
Saves space, reduces cost – One Multiseal® low friction seal can replace two U-Cups in many applications.
Less force, better seal – Lower breakaway force and reduced operating pressures make them ideal in reciprocating applications.
The right fit – Multiseal® low friction seals and X-Rings compression seals will fit in standard O-Ring grooves

The x-ring holds lube better within the pins...
Chain does have the advantage of being a bit narrower, making it an easier option for wider tires. Also, Chain swaps are easier, and more options for changing your ratios.
Lastly, if you use a good quality sprocket and take care of it, you can usually get two chains worth of use (assuming quality chains)
On a personal note, chain feels more lively to me, and has a certain sound that I like. To me, it just feels more alive to me.
You are 100% correct on the belt requiring less maintainence, which makes it a valuable option for many.
Shaft is also a good option for those who like high reliability and low maintainence