.177 the one to go for for HFT?

[Chris2012]

.22 can be more stable in the wind due to the greater weight. However, you really need to be exact with your aim points because of the bigger curve the pellets takes along its trajectory, again due to the greater weight. Shooting with .177 is a bit more forgiving. For example, from 17 yds to 45 yds all my aim points will fall within 1.25 of a mildot so you've a greater chance of scoring with a poorly ranged target.
Plus they're a few quid cheaper per tin

[Biker_Bob]

As mentioned, 177 gives you a flatter trajectory and makes it easier to hit targets at varying ranges.
Also as mentioned, since everyone shoots 177 you're up against very stiff competition. If you go for 22 you'll have to work a bit harder, but you'll be competing in a very small group.