I got a 2 post. It takes up less space and gives good access to what you are working on. The reson to get a lift is to work on your car. If you are looking for more storage space build a bigger building.
Easy to buy a lift. Not so easy to add onto shop. Seems no matter how big a garage/shop you build it's never big enough. Yes a 4 poster is inconvenient for working on some things. The plus side is they most often come with wheels and can be moved even with the car on (though not real easily). When the lift is up in the air it's pretty much out of the way especially if you have the extra tall one. Jmo.