No choice at all buy the OS! SK- maybe ok and maybe not, some run ok but I have seen (not heard about), actually seen and used some that were ok but a couple of others had to have the carb replaced to run half way reliably. The Super Tigres need a lot of breakin and the carbs can require a lot of fiddling with to run right. The OS will normally be close right out of the box and they are very easy to tune and will last a long time. Thunder Tigers are another good choice.
IMHO
Fred