IMO, Renzetti is one of the top vices on the market, but unfortunately not cheap.
I've had my Presentation clamp model for over 30 years now and it has never failed me, travelled to many distant locations and always allowed me to tie everything for size 14 ( I don't tie smaller than that ) to 3/0 Pike flies.
Warranty service is good if needed and they certainly stand behind their product if you need info or advice............and made in America.
Cost is high, but if you are serious about fly tying, you won't be disappointed with this vice. Comes in a variety of models these days at varying price ranges.
The best advice has already been posted by others, so do yourself a favour and go to a good fly shop, try out the different vices available and purchase the best one that suits your budget.
Many of us have all been there before, buying cheap equipment to save $ and eventually moving up to the higher $ stuff because cheap equipment just doesn't always do the job.
These days, everyone is unfortunately having to deal with the high costs of everything, so once you do find a good rotory vice that suits you and your budget, you won't be disappointed as to how much it will improve your tying skills and enjoyment.
My best advice............do the research, purchase the best you can afford and enjoy using it!...........