Electrical for anything to do with oil.
Defi are probably better quality but dearer. Both however will do the job fine and are about the same to install.
Or you could find some nice Jap gauges (Blitz, Greddy, HKS etc), but with the dollar the way it is they are dear as hell. Having said that, i have the Blitz white faced gauges in mine and love them to death, however they don't make them anymore