I've been running a Tasco varminter in 2.5-10x42 with mildot reticle for almost 4 years. Never had an issue. I also use the Bushnell series on my other 10/22. An adjustable objective is nice, provided you know how to use it. Bushnell scopes without an AO are factory set to be parallax free at 50 yards. I have used a non AO scope and find no problem hitting what I aim at.
Either way, you won't go wrong with a descent Bushnell for your rimfire. What I feel is more important when choosing a scope are things like field of view and reticle pattern as well as the use of target turrets. If your shooting is mostly short range than I'd say a standard duplex reticle or 30/30 as Bushnell calls it would work fine. I often times like to shoot at distance with my 22 (sometimes out around 200, I know its crazy but sometimes fun!) so a mildot reticle really aids in adjusting my elevation without adjusting my settings. If you like playing with your settings and working the numbers for different distances then target turrets might be what you need. I would stongly suggest you map out what your style of shooting will be (most of the time) and then decide on what specific model of scope to use.
CF