To me it is a very personal choice, at the top end there isn't much difference in quality. What I mean is that you are paying for top end engineering, and, mostly, you'll get it. The best thing to do is make a list of your requirements. Decide how much you want to spend, and use those as a filter. Once you have done all that if you can try tying on each vice left in your short list. This may not be easy but one will stand out as giving you the most. The things to consider are:
Rotary or fixed?
True rotary? (Can be set so the hook shank rotates around the center of the shank) Mostly used in tying larger flies (Salt water and pike)
Fixed tying position or mobile?
Traveling?
Hook clamping method. Some vices use a collett which force the jaws closed by a cam. Others use two plates forced apart with a pivot operated with either a cam or screw. Spring jaws that are normally closed and open with a lever to place the hook. An unusual method, but some like it, is a hook or loop which pulls the hook into a grove.
Ascetics, you'll spend a lot of time looking at it.
Clamp or pedestal? Consider your tying position. My tying position will not permit the use of a pedestal.
There may be other considerations, that's a start.

When I bought my first top end vice I was amazed how much difference it made. Tying became much more comfortable. Now I can sit for long periods tying without strain. Also I can cope with just about any tying job I may need to.

The lack of any recommendation of any vice is deliberate. I haven't tied on all the available vices so can't say one is better than another. You are not looking for the "best vice", but the best vice for you. Good luck with your search.

I hope you have a swift and safe return home.
Cheers,
A.