I use a beard trimmer, VS Sassoon iTrim. I'm on my second one as the first f**ked up, stopped holding charge and would even slow down/stop while shaving with it plugged in. I sent it back and they replaced it with an apology letter and all that, so pretty hassle free, but the replacement one started doing the same thing within a year I'd say.
Still got it and it still gets the job done, but doesn't hold charge no matter how long you charge it for, and randomly slows down while shaving even when plugged in and when it's been left charging for an hour or so.
I think I'll try a Wahl trimmer next