I have a Nikon Prostaff Rimfire Classic in 4x that I've been especially pleased with.

You can check it out here (where the price is as good as I've ever seen): http://www.budsgunshop.com/catalog/product_info.php/products_id/52269

For that money, you're getting some pretty clear glass, & I've never had even the 1st tracking problem on any of the 3 Prostaffs I own. The parallax setting is for 50 yards. I think that's perfect for what I want it to do, but if you want a farther setting, you can look around for other models.

Good Luck,

FC