I have to agree with that; however, I would add that my experience with 2005+ Mustangs (that's years 2005 and newer, not more than two thousand and five different cars!) might be useful to someone who hasn't had a recent product of the Flat Rock Folks.
I had a 2006 V6 Premium automatic. It was really nice, and if I hadn't had a lot of interest in handling characteristics, stock would have been a good enough car for daily driving and pleasant cruises. As it was, I added springs, shocks, sways, wheels and tires, and it was SUPER nimble and a canyon carver deluxe; not so good in the ride-quality area, but passable. Power was more than adequate for ordinary uses, and my son-in-law the master autocrosser could really make it fly.
I also liked the sound of the dual exhaust better than the V8 sound, on a sensual scale. The V6s don't get the credit they deserve. GT sways and dual exhaust make them 80% more enjoyable with no other changes.
The Premiums usually come with enough options that there isn't much in the way of factory options really worth adding, for my uses.
Underlying it all is the question: do you want to have a base to build on or do you want to buy and enjoy. I would not hesitate to go for the V8 base if there is any possibility that you'll be thinking "I could have had a V8". Your base GT will be a little quicker than the others that are option-laden. After a couple years of the V6, which I really liked and was satisfied with, when I had a chance to get another Mustang, I took the V8. Just because I wanted to have the V8. Mine is a little heavier than base in the option list (GT/CS), but basically the fact of V8 power is the only thing you can't get in a Premium V6, with a little industry and ingenuity. Finally, when I felt the need for an automatic convertible, I again chose the GT/CS, for its features and power (and it gets better MPG than the V6 I had!).
Speaking to the order-options I would not want to do without: the Comfort group, which includes the power-adjustable passenger seat, because my wife is altitudinally challenged, and can hardly see out without it, or a cushion.
I'm not much of a music-in-the-car listener. I like the sound of driving too much to have it on when I'm rolling, and when the car is parked, I'm not driving, so I'm not in it to listen. I understand the Shaker 1000 is forty-five pounds of useless drag for people like me. Satellite radio was nice out in the wide-open spaces of West Texas, but otherwise, useless expense, for us.
Come to think of it, unless you have other special interests or needs, that's about it. They all are good at what they do; plenty to like in every one of them. Only you know your requirements and needs. Most of what isn't on the basic car is icing on the cake. Pick what you like and need, and enjoy it.
PS: Black and White are the fastest colors.