Welcome to the board. The Regal Medallion is a fine vise-- I've been tying on one for 25 years--- bullet proof design, hold hooks of all sizes like a bulldog, and is a "360 degree rotary" which lets you flip the jaws to view the fly from all sides--- as opposed to a "true rotary" which rotates inline around the hook shank for rotary tying techniques. The spring clamp jaws grip hooks of all sizes with no adjustment---- I regularly tie sizes 22 to 6/0 with no adjustment in the same jaws. You can also adjust the angle of the jaws up and down which makes it great for tying flies like clousers, (after you tie in the eyes, angle the jaws down and flip the hook to tie in the top wing on the inverted hook) and for tying small flies (by angling the jaws straight up and setting the small hook in the vise to give you room to tie in tails).
The Regal INEX is less expensive than the Regal Medallion, but has a fixed head (doesn't rotate, and doesn't have an adjustable angle). It also holds hooks very well, but for a bit more I'd go with the Medallion. You may also find deals on used Regal Medallions out there, and since they're built like tanks, it wouldn't be too risky.
The price of the c-clamp is significantly less than the pedestal base model, but the base model is very sturdy and I prefer the versatility of a base since I tie all over the place and don't have a dedicated fly tying space. At least it's not supposed to be dedicated to fly tying (from what I hear it's apparently supposed to be a dining room table...) The base is sturdy enough that the vise isn't "tippy" when tying stuff with a lot of thread torque like bass bugs, or big SW flies. The c-clamp would be even more solid for tying that kind of stuff.
Regal makes a "true rotary" called the Regal Revolution for big bucks, but there are many others that you might want to look at first if you were looking for a true rotary.
Although I'm VERY happy with the Regal, everybody is different, and it would be ideal if you could try some different vises out before you buy. Since you've actually spent some time tying on the AA, you have a big advantage over other folks that are just taking tying up for the first time.
In addition to the vise review link that jimw posted, here's a good article on different vise designs and features:
Fly Fishing Gear, Fly Tying Vises - MidCurrent
The good news is that you have a lot of great options.
good luck and keep asking questions as you narrow down your search.