Of those you listed the 4200 is the best optically, it also carries the highest price tag.

I agree that for bigame hunting high mag scopes have more pitfalls than +'s. Though it depends I guess on your deer hunting situation, if open terrain/long distance shooting it probably won't matter if all you can go down is 6x but if you ever hunt in tight areas and/or larger game in the future you may be wishing you could drop her below 6x as well. For varmits and target the larger power range is handy for sure. If dual purpose is your goal for deer/varmit and more functionality in the future with one rifle/scope comboyou may also consider somethinglike a4-12/14 instead.