I personally prefer manual over electric, Usually more accurate but there are some of either that can be crap. Electrical has the advantage of not having the chance of a leak though so it's pretty much up to you.
+1 on Charlie, Mech's are accurate but can be a PITA to install. Electric gauges can be mounted almost anywhere the wire's will reach, but I would verify with a mech gauge to make sure you get the right readings.