I just made this decision recently and posed the same question while making my decision. From your list, the Extra and the Cap are considered too advanced for a second plane with the Ultra Sport a bit more forgiving but still pretty advanced in comparison to some of the others. Your best choices would probably be the Super Sportster or the SE. The SE can be especially wild if the control throws are set to the extremes but if they are kept tame it can be very forgiving. I considered the SE myself but I ended up going with a .60 size plane.