Regardless of the quality of any bottle jack you might want to add to your RV's mix ... make sure you get one with as high a lift (not including the screw top) as possible, for flexibility in any situation, and one with as high a tonnage rating as you can afford, for reliability.
I carry a two-stage 12 ton bottle jack in our RV with plenty of wooden blocks to go with it. The blocks are to put under the jack in soft ground and/or to hold the axles high enough off the ground after you use the jack to raise the axles - since you never want to work around any portion of a raised vehicle with only the jack holding up whatever you raised up.