1. USB. How long will it be around?
2. Firewire. Will it still be here? Some laptops don't have expansion slots.
3. Thunderbolt. Hardly anything on the market at the moment.
4. ADAT. An interface with adat could probably work in many environments in future, even if other interfaces become obsolete, providing you can still buy PCI cards with it.
5. PCI. All the UAD cards are on PCI (for example).
6. Standalone mode. Important if you want it to work away from a computer, although some have to be configured using the computer.
Any comments would be welcome (and not, I'm not an 18 year old student).
I now have a good laptop to try out so I have USB ports and an Expresscard/54 slot.
Jack of all trades, master of some.