Years ago, I had a nightmarish stint with a Maplenoll table that had an air bearing arm. But, this was a very cheap table with a very, very cheap air pump. The pump was the source of the problem.
I know of three brands of arm/tables offering tangential tracking arms. The Kuzma arm, which I saw at CES, is quite a well-engineered arm (as far as looks). The pump, high quality braided tubing, air plenum/filters/dehydrator looked absolutely first rate. Walker makes a table with an air bearing arm, too.
Clearaudio makes an arm that works without air -- it uses a very low friction quartz rail and sets of wheels that ride on the rail. It looks delicate and fiddley, but I've used it and it seems to work without hitch as long as the table is set up correctly.
I've heard, off and on, that Air Tangent will be making its arm again, which would make four different manufacturers. I bet, if you came up with the cash, Rockport would build a Sirius table with its arm bearing arm.
Tangential arms may have some obvious advantages, due to correct arm geometry, but they have their own theoretical tradeoffs. For example, the effective mass in the vertical plane varies greatly from the mass in the horizontal plane. The short arm tube also means that VTA tends to change radically when the arm moves up and down on warps and even for differences in the thickness of records. There are also issues with sloppiness in the bearing, and how effective the bearing is at draining vibrations transmitted down the arm.
I don't think there is any one design that is theoretically superior in all respects. Besides, differences between theory and practice complicate choices even further.
