This list can get long fast but for me:
- Adequate space (including up) to comfortably work around the car
- Lift (preferably 2-post with enough height for a 6+ footer to fit underneath
- Lots of storage cabinets and one or two high quality tool chests
- High quality floor sealer/paint
- Good amount of work table space
- Nicely outfitted bathroom
- Fridge and sink
- TV/Stereo
- Power outlets *everywhere*
- Secure/quiet garage opener & door
- Heat/AC
- Water tap & hose/reel