My personal experience is that the .22 versions shoot far smoother. In theory the .177 offers a flatter trajectory than the heavier pellet but at pistol shooting ranges and with the quite high power output (well for an air pistol!) the .22 isnt that 'loopy'. When I used to shoot at a field target club, after some practice I could achieve good accuracy at 25 yards and sometimes further.

From a technical perspective .22 is the more efficient of the two.

As a matter of interest I also prefer lower powered pistols such as Webleys in .22 - it just feels better.