For me it depends, the dining plan was a good enough value for us to book a package in 2005 and sometimes the offers that they send in the mail are a better deal than buying the components separately.
I'll price both and I'll book what I perceive is a better value. Before the advent of the dining plan, we pretty much did room only.
The new dining plan doesn't have as much value as the prior dining plan so room only is looking more attractive right now. I will crunch the numbers on the deluxe dining plan to see if that is a better value.
In summary, normally room only is a better deal, the room, the tickets, and the transfer purchased separately are almost always (there are exceptions) less money than a Disney Package.
Disney packages offer convience, and those pretty luggage tags.