If the paint to barrel match is good, then open and closed bolt guns are equally accurate.
Closed bolt guns have problems if the paint is too small for the barrel, because the ball is allowed to roll into the barrel before it is fired.
The cocker and the angel will be around the same air efficiency too. The older angels are slightly more efficient than a cocker, the newer ones slightly less.
Really there is no such thing as a 'back player gun' or 'front player gun'.
How your gun is setup reflects whereyou play.
For example if you played up front, you would use a small 0.74l air bottle.
If you play at the back, where you would carry more paint then you would need a 1.1l.
Or slap a newton valve on your angel and play back with a 0.74l