Like with a lot of things-how much ya wanna spend? I personally like higher magnification scopes, and would suggest them. However, others do not like them as they narrow the field of view.
One I have on a coyote rifle is a Simmons Whitetail 6.5-20x50. It is a discontinued model, and is worth the money at the very discounted price it is offered. Crosshairs are a bit thick for fine target shooting, but are easy to find in the field. SWFA has still has them for $99. I would have bought a 40mm scope, but no one has them in 40mm anymore...and beggars can't be choosers! It has a nice textured finish, and mine has taken a year and a half of hard hunting (and about 1500 rounds at the range) with no problems.
A good mid-price scope is the Bushnell 4200 or 3200 series of scopes. I picked the 4200 over a Burris and Leupold VX-III and am not sorry. Others have scoffed, but to my eye, it offered better clarity and brightness than the others. I have used the others, and was very happy with the 4200 in the field when compared to the other two. Theopticzone.com has some of the best prices on them.
I talked my dad into a 3200, and it is almost as clear as the 4200. Either one would be well worth the money.
Also, Natchez has Browning scopes on sale. They are basically a 3200 without Rainguard coating on the lenses. I just ordered a 4-12 for a low-buck Savage .270 carry rifle. They also have the 5-15 on sale. Prices are $189 and $199, respectively.
The 4200 I would reccomend for varmints is the 4-16 or 6-24 (preferably the latter), the 3200 I would use is 5-15.
Of course, if you can afford a Schmidt & Bender, US Optics, or Nightforce scope buy it! If you want to step up to one of them, I can give you a couple of places that have excellent (but still not cheap) prices on them.