Catching his breath alongside a road near Seattle, WA USA
1999 K2 OzM, 2001 Aegis Aro Svelte
The UltraSensors have much higher quality padding than the Attacks. Additionally, the UltraSensors are 8-panel vs the Attack's 6-panels (I have older Attacks) although I think the newer Attacks are 8-panel too. The lycra of the UltraSensors also feel nicer to me. The Quests look to be what the older Attacks were and are only 6-panel.
I like the Ultrasensor's for their fit and feel, but I really think that Performance's Elite actually cushions the tush more. I rode back to back 70 mile plus days using both and found that they Elites were more comfortable. Plus the fact they are much less in cost makes them extremely attractive.