We've had 5th wheels with slideouts since 1996. All have been electrically-driven mechanical (i. e. , gear-driven) designs, and we've not had any problems whatsoever with any of them. Having said that, the modern electrically-powered hydraulic slideouts seem to be pretty well sorted out as well.
The type of slideout drive mechanism won't be the "make or break" decision when the time comes to purchase our next 5ver.
Rusty