I had a captivate and thought the same thing, no more samsung, but after comparing the sensation/evo3d/optimus3d and sgs2 the sgs2 stood out on top. It has the quickest browser, thinnest design, 2mp front facing camera and the nicest screen out there.
Its ext4 now.
The "thin design" also concerns me. I'm rather worried about how sturdy it will be. My phone lives in my pants pocket most of the day and constantly getting leaned up against stuff.