THere are some Cougar waterproof winter/rain boots that have a zipper. I think they are all going to be more expensive than the TSV.
These below are my Cougar waterproof boots that I purchased about 8 years ago. I adjusted the buckles once. Then just slide my foot in, never having to tie, zip, or adjust.
If you do find a pair you like, I can attest that they are fantastic winter boots! Good luck. 
