I've used several different types of tip ups and found that there are factors that I like from each of them. The T-type tip ups stand up taller hence the flags are easier to see, especially when getting some precipitation. However, I've also found that I tend to get more hookups, without tripping the flags on these. It's just a matter of how the flag "hooks" onto the mechanism.
I more regularly use Polar's (the rail type, not the round ones). I like these because there are several different sensitivity "settings" so you can fine tune just how easily the flag is tripped. They take up less space than the round ones, but a little more space than the T-type. The rail type Polar's fold up quickly and easily, whereas the T-type, sometimes you gotta fenagle them a little to get them to fold up the right way. I also like how the Polar's have the "T" on the top so you can watch to see of line is being taken out as you walk up to them.
The only downfall with the rail-type Polar's that I have found is, with wind+cold weather or precipitation, they can get covered easily of freeze to the ice easier than some of the others. Which often makes them less visible from a distance than the T-type.
Overall, I think it's a matter of personal preference, and I like the tuning ability and simplicity of the Polar's.
