I have the FVD Tune on my car. I should have done it sooner.
I quite like it and it did make a difference, but to be fair, I had all the bolt ons added with the exception of the header (work in progress.)
I think in terms of ease, they are all more or less the same across the board - you install the software onto your laptop (mostly Windows) update the firmware of the tuning device (if applicable) and then plug it in to your car to capture the stock image. You then upload the stock image into your laptop, send it off to your tuner, and they send you the updated file. Take new file, upload to your car, and away you go.
I can't speak for the other vendors but before you buy, see which vendor you get the best response and support from. That and read through their software installation procedure. FVD for me provided a lot of support and was very responsive during regular business hours, and the bonus is they have a team in Germany who will reply to you before you get up in the day.
My only "gripe" (read; first world problem) is the software where you need to disable firewalls, disable anti-virus and stuff like that before you can update the firmware of the device. This is more or less a two time thing because realistically, how often are you going to flash your car's ECU? Maybe a few times and that's it.
Any how, the tune has really changed the car. I'm still getting used to it and it is quick, but I am loving it. If you have bolt ons, get the flash. If the car is stock, I would spend the money on maintenance and necessary repairs.