We use mostly Ford-Smith hoists,the TEC series.They are cheap,easy to install,and require almost zero maintenance.They are above ground hydro electric,with a clear floor,and just a couple of small lines overhead (hydraulics and air locks).The smaller ones (9000Lb) are all asymetrical (which means the car sits further back,so you can open the door) and they will lift my 97 Dodge,2500,CC,diesel,long box,wieghs 9000 Lbs +,no probs.We also have a bigger 12000Lbs hoist,but they are much more expensive,and tie up alot of floor space.If you want to get one,go big.You can always put a small car or truck up on a 12000 lb (or larger)hoist,but you can't put an F550 on a 6000 lb hoist.Ford-Smith just updated their TEC series with a 15000 Lb unit.I wouldn't recommend an inground hoist,too costly and hard to repair and maintain.Here are some links that may help,or e-mail me for more info.I can also get them for you at cost,including installation,through our buying group.Just make sure,like mentioned above,you have (or build) the proper floor to support it.BTW,you may also need special permits and insurance to have one as well,just check beforehand.
http://www.fordsmith.com
http://www.rotary-lift.com
http://www.sarlifts.com
http://www.westernhoist.com