4-20x50 does not have tunneling. It does have a fairly narrow FOV, which happens when you try to combine a moderate diameter eyepiece with long eye relief. If that is what you are seeing, then the new 4-25x50 Toric will suit you better. I have one here and it is a nice scope.
Burris XTR3i and XTR Pro doe have wider apparent FOV, so if you that is a strong preference for you, you should consider them. I have both of them here and they are absolutely going to land on my list of recommendations. I am quite impressed with both.
Athlon Ares BTR is a very nice scope for what it costs, but in terms of image quality, it is not quite in the same league as the Toric unless you happen to have an absolutely cherry sample of the Ares and the worst Toric ever made. Where Ares particularly suffers is in high flare situations. That is a common problem for many modern higher end Chinese scopes: they seem to not quite have gotten a handle on flare control yet. Overall, many modern Chinese scopes are exceedingly capable and at the rate at which they are improving, the Japanese should be very concerned.
ILya