Power depends to a large degree what you do with the scope. Will you use it for hunting, or will it be strictly a target scope?
And if used for hunting, the type of terrain will also figure into what might work best. Field of view size is extremly important
for follow up shots where recoil (could) cause the target to be temporarily lost from view. Where many of us hunt the hills we shoot at are totaly
tree covered. One or two steps after the shot is sometimes all thats necessary for you to lose the animal from your sight. If it runs off any distance
before stopping again its even worse. Without a spotter watching and keeping things sorted out you could be in plain words, screwed.
The type of equiptment you use to shoot with can also play a large roll in helping stay on target following a shot, and might allow for using higher power with less field.
Practice by picking a small rock in a small opening between trees. See if you can stay on following the shot and how hard it is to find it again.