Seems, I'm in the minority here, I've had troubles with the Hydro in my '86 C10, rotted lines, bad master, 3 slave cylinders (C10 is my DD), but the manual linkage in my '73 has never bound up, never given me any troubles.
I'd say manual linkage all the way, unless your doing hard rocks all the time where the thing is twisted constantly. But even twisted up, my '73 never bound up where I couldn't release the clutch.
The hydro setup in my '97 is even worse, the slave cylinder is the throwout bearing (they call it a hydraulic slave cylinder), goes bad about half way through a clutch, wrecking the clutch disc by spewing fluid all over it. That truck is a pain in the arse to remove the tranny/transfercase too, and nothing like having to do it unexpectedly with half the clutch life left, which I've done twice already.
Anyhow, my vote is for good old reliable manual linkage.