Qwert, looks like you've got some company from Singapore here too! I just bought a Sauter Delta (6 foot) myself and have been very impressed with their uprights as well. Sauters in general combine a firm touch and a powerful tone when called for, trebling sparkle and deep bass, and I would strongly recommend you to try a few of them before making your decision. Not to mention an excellent dealer - one of the few I could genuinely connect with, and who provides top notch service. I cannot overstate the importance of this last point.
That said, I think the other choices you have listed are all excellent pianos that I considered during my own search, but for various reasons decided to go for the Sauter in the end, and in the process doubling my original budget. I liked the SK-3 (though I was comparing the larger SK-5 with the Delta). Steingraeber 130 is a good upright too, powerful like the Sauters, and with a firm touch. Schimmel is a nice, sweet sounding piano, more affordable than the rest, but to me, at a lower level of quality compared to Steingraeber.
Good luck in your search and keep us posted!