A good vise is made from good quality, amply-proportioned castings. A good vise has good smooth screws and perhaps real thrust bearings to take the load. A good vise has the base machined parallel to the slideways on the vise top, in both X and Y directions. A good vise has nicely finished hardened jaws that actually nest on the base of the vise when you take them off the first time and put them back on, they are still locating properly. A good vice has the capscrew counterbores in the jaws large enough to clear the eccentricity of the capscrew head. A good vise has an 'anglelock' feature on the movable jaw which helps pull the jaw down to the slideways when the vise is tightened up. A good vise feels solid, not spongey as you tighten it up, it feels like it reaches 'tightness' without going another 1/4 turn, and still not feeling positive about it being tight.
A good vise has a solid enough fixed jaw that it will not move more than a thousandth or two when tightened, and that therefore stays reasonably square to the slideways.
A cheap import will see you through until you figure out that you need better. What's really tough is making two import vices line up with each other if you have need to use two vises at once on a part.