The factors to consider when choosing Mole grips/locking pliers are:
The shape and size of objects with which they will be used
Where they will be used
Convenience
Price
Shape and size of objects
You will make most effective use of your Mole grips/ locking pliers if you match them to the application. For example, needle nose Mole grips/locking pliers are best used on small or hard-to-reach objects.
Some Mole grips/locking pliers can be used for more than one application, but they are usually best suited to one.
You should also make sure that the capacity of the grips/pliers is right for the object or surface you plan to use them on. (See: What Mole grips sizes are available?)
Where they will be used
Larger jaw Mole grips/locking pliers are usually only used in industrial settings.
Long reach Mole grips/locking pliers are ideal for reaching into confined or awkward spaces.
If you’re working at or above head height, or at an awkward angle, then choose grips/pliers that are relatively lightweight, to make the job slightly easier.
Convenience
If cutting wire is the main reason you would be using Mole grips/locking pliers, then buy the ones with a built-in wire cutter.
Automatic Mole grips/locking pliers don’t need adjusting after every use, so if you need to save time then these would be the ones for you.
The triggerless release of no release lever Mole grips/locking pliers makes them easier to use in confined spaces because you simply have to pull the lower handle to release the jaws, rather than manoeuvring your hands to the end of the handles as with some other types.
Price
Mole grips/locking pliers are priced about the same, so if you only want your grips for occasional use then the cheapest pair will work for you.
If you want your grips for regular or everyday use, however, then paying a little more and buying from a reputable manufacturer will get you a better quality tool.