Yes a dyno tune is the most accurate. But I disagree with email tunes being bad. A canned tune ( at least to me ) is the ones that come preloaded on a tuner which are complete crap I agree.
But a solid email tune based on your cars ECU code and specific mods is just fine for a fairly basic setup, really only needing to get into dyno tuning if running massive cams or f/i. They dont ( or at least, shouldn't be ) creating it based off other people's car whatsoever. The tuner will have a baseline for that specific ECU code on your engine, then go into the edit tables on the SCT software to change them for whatever performance mods you have. For the S197 cars, AM, BlowbyRacing, and Brenspeed all do very solid tunes. Will a dyno tune be more accurate? Yes. But bang for buck, a good email tune willl suffice for your setup.
I can speak only for SCT software as that is what I have used extensively in the past. Haven't touch the Diablo, Edge, Hypertech ect ect