.177 or .22 for me?

[Loki_762]

I have been seriously considering a high powered pellet rifle for dealing with pests around my house. Living on the edge of a greenbelt, there is plenty of critters out there that are not welcome in our yard, and I need a means of keeping them out. Most of what I would be shooting at could be taken with a .177 moving at about 1000 FPS, I would imagine - things like rabbits, crows, and starlings. However, within the last few weeks, the raccoons have begun to get pretty bold, and have even gone so far as to come up on to our deck in the middle of the night. We have cats, and we really don't want them getting torn up by raccoons. So, my question is this: will a .22 be a better gun for me, in case I have to shoot a raccoon, or will a .177 suffice? I am thinking of getting the larger caliber, thinking that I want it to be able to humanely kill ANY of the animals it hits, if I do my part right. Also, can anyone recommend an air rifle that they feel is a good value and good quality for the price that is under the $200 mark?
Thanks for any advice you can give me,
Loki