Speed Density or MAF

Okay guys I'm thinking of taking the plunge to fuel injected. I haven't read all of the info on chevythunder but will get back to it later tonight.
 
The one nagging question is which system is more suited for my desires, speed density or mass air flow. I never know when the bug to change something in my engine is going to hit me. So what are the pro's & con's to each system.
 
Is there an end user programmable control unit out there? Most of the ones I see you have ot buy a  chip, so how do you change the map to get the most out of your engine. Certainly things need to be or can be tweaked for the most out of your setup....right?
 
Give all your ideas & input please.
Thanks,
CCar

Are you going to use a factory controller or a racing type after market unit?

Is there an after market unit that can be configured by the end user? I may try to piece together a setup so the ECM is going to need to be thought out. Basically I want to be able to take it to someone locally who can hook it up to a lap top or their machine & fine tune the setup once I have it in the car. From all I've read you have to get a chip made.
Thanks,
CCar