Den't look like anyone else is going to answer, so I'll give you my thoughts based upon my own limited experiences.
Buy a machine that suits your current and ongoing needs. If you think that you are likely to want a bit more capacity later, then buy a bit bigger machine now.
I wouldn't call a 1200Lb machine small, in fact many contractors have made their living using such machines. The bigger the machine, the faster you will move your dirt. Get a 4 in 1 bucket. A skid steer is only half a machine without one. While there are better buckets for specific jobs, a 4 in 1 is the most versatile implement you can put on your machine.
If buying second hand, don't buy a high flow machine unless you need it. My reason for saying this is that a second hand high flow machine has probably been worked a damn sight harder than a standard flow unit. Around my area, wheeled high flow machines have generally run asphalt planers, which are hard work.
A machine that uses a lower revving engine will be a better prospect than a machine that screams all day if buying second hand. Machines in the same class can have rated engine speeds from 2000 to 3300RPM. Obviously, the 2000RPM engine will outlast the screamer.
Do a little research on parts pricing and service, some machines are very expensive for ongoing service items and repairs.
Go with a dealer that you can work with and who will work with you.
All the machines you list are from reputable manufacturers, so final choice will be down to price and features. Perhaps if you tell us a little more detail on what you are planning to do with your loader, we could be more specific.
