Though I prefer jQuery. But sencha also looks promising. They started investing heavily on web based mobile apps from the very beginning. Apart from sencha, Sprout Core also good player in this field and provide a quite complex framework for the mobile based development.

Was it really? I find that interesting, since jQTouch is much closer to jQuery Mobile in syntax than Sencha (which is a giant Javascript Object)

Yes there is a bifurcated development path. I prefer the HTML-friendly approach (JQtouch) as opposed to the monolithic Javascript (Sencha Touch)