It used to be the electrical gauges had a short sweep (90*) and mechanical had full sweep (270*=more precise) but I've seen some full sweep electrical gauges in the catalogs nowadays. I would opt for mechanical but keep in mind they are more difficult to deal with snaking the sensor without disconnecting the line since they are full of fluid and can't be taken off without ruining the gauge... electrical are easier since you can run wire wherever you want.

two cents,

-Chris