with a more expensive floor jack you get a better pump. a good jack should only take 4-5 pumps to reach full height.. the POS. canadian tire ones take like 39 pumps. that's the only difference i know of other then the larger more expensive ones are less likely to twist and fall over crushing you under the car.
Princess Auto has some nice jack for a decent price.
E30 Stuff For Sale: Clutch Fan and Shroud, 4 Pack Ignition Coils, ATE 750il MC (New), Offset Trailing Arm Bushings, m42 Valve Cover (Clean), M10 Engine Mounts (New), M42 Injectors,