LOL!!
I would say:
Vacuum-Easy
Requires very little knowledge. Good for the inexperienced, particularly on predominately street driven cars with automatic tranny and high geared rear end. Out of the box, will give better gas mileage in many cases.
Mechanical-More difficult unless one takes the time to learn how carbs work and devotes time to tuning the various circuits. Faster and better suited for higher performance cars with manual trannies, lower gears, and/or higher stall converters that properly match the engine's characteristics. CFM should be at least twice the cubic inches for max performance. Oh, yeah...more fun and who gives a damn about gas mileage!
EFI-Leaps and bounds beyond the others-The only way to fly if you can afford it. Throttlebody injection for a mild street combo. Port if you are serious about extracting the most performance, the best drivability, and the best gas mileage. Throttlebody is largely self tuning these days. Port self tuning is also available but best performance comes to those that are willing to learn how to manipulate the fuel spark tables, or those who have a smart friend or an experienced tuner...
