I don't trust hydraulics except for a few minutes. Personal phobia maybe. Your mileage may vary.
I carry 4 mechanical screw bottle jacks:
2 x Isuzu (ex 4x4's, $40 the pair from a wrecker), which are in constant use when parked up - to level the van on a site, and to take the weight off the tyres when parked at home.
1 x Toyota 4x4, there as a spare and because it's a little newer. $40, wrecker again.
1 x old but very low profile job: useful for getting in under the chassis if all else fails.
All are operable with a handle chucked in the trusty Hitachi drill, so are effectively power lifts....
The beauty about screw jacks is that they are set-and-forget: absent a catastrophic mechanical failure, they will never sag.
I'm also in the process of adding two high-level jacking points to ensure I have a jacking point which will be usable in a flattie/soft shoulder situation, where the chassis may well be practically on the ground. (see links at viewtopic.php?f=17&t=17678&start=96#p150827