I was fortunate enough to work in a old school barber shop & get trained by the old boys, All of preferred,Andis,Whal or Oster.....new brands would be tried but never stood up to the 3 tried & true!...I don't recommend anything cordless ever, its lacking in power & is only good for "stylists" whom do a "fade",poorly with scissor over comb & just use it for edging/neck lines.
My personal faves are: Andis master(pic) its all metal which I like but more pricey, Whal 5 star or senior. Both are good for freehand,clipper over comb & guide cutting & replacement blades are easy to find. I have cut 20-30 heads /day for about 6 years full time & not had a problem with these clippers so long as you keep them oiled good!