For the hotter rimfire rounds like the 17s, I think the 4-14x mag range is about ideal.
The problem is good scopes with AO in that range are a bit pricey.
One of the very best buys in a rimfire scope is the Mueller
APV (All Purpose Variable)
Only costs about $115 most places. has nice optics tracks out well and has AO. Good size and power range. I owned one for a while a few years ago and liked it very much.
Also, Mueller backs their stuff pretty well.
The guys over on rimfire central have always thought highly of them. If you can't swing a Leupold, etc , maybe you should check them out.
SWFA carries them as well as other online dealers-
http://swfa.com/Mueller-45-14x40-APV-Riflescope-P9136.aspx