The basic design is a matter of personal taste. I went with a twin-screw chop on the front, and a "Record" style end-vise and have been happy with both choices. My prior bench was a traditional European bench (one designed by Tage Frid and for which plans can be found in an old Fine Woodworking magazine). Because I liked the "arm" on the front vise on that one, I mounted the twin screws on my front vise off-center, leaving an "arm" of about 8" at one end which comes in very handy.
The other design element to consider, especially if you do stuff other than lutherie, occasionally needing to clamp large pieces of stock, is to make the front apron and the face of the two front legs co-planer. Bore 3/4" holes in the apron and the face of the legs to accommodate holdfasts. For that matter, be sure to bore 3/4" holes in the top for holdfasts also. I find them to be every bit as useful as the vises and conventional clamps. The ones from
Grammercy Tools are particularly nice and not too expensive. Making the face of the legs co-planar with the front apron gives you a very stable large flat surface on which to clamp panels, doors or big live-edge slabs.
I agree with the comment above re access to all sides of the bench. However, we don't all have a shop big enough to accommodate a workbench out in the middle of the room. I mounted 3" polyurethane double-locking casters on the bottom of the legs of my bench, and to my surprise, that bench does NOT move, except under the most extreme circumstances, like hogging off huge amounts of stock with a hand plane, and I very seldom ever do that. It is thus very easy, when I need to do so, to unlock the casters, roll the bench into a more advantageous location, then put it back against the wall when the operation is finished. I'll admit, being solid maple my bench weighs a TON, plus I have PVC floor tiles, both of which helps keep the casters from scooting when subjected to high lateral loading.
Something to think about if you do this and you have a shop on a basement floor or some other surface that isn't uniformly level, is a way to level the top on the legs when moved to a different location. Even if it isn't movable, think about how you will level the top. I don't know about you, but I hate a workbench that everything rolls off of. If interested, I can post pictures of how I accomplished this to allow the top to be leveled using a hex key.