The answer is really "it depends" depends on who is doing the work, and what you want for a finished product. As others have mentioned, a single stage will probably give you a more original look, a basecoat clearcoat will give a shinier glossier deeper finish. I painted my car myself and used a single stage urethane from TCP Global, good paint, about half the price or less of equivalent PPG and other name brand stuff. BTW, I took a bodyshop class and the instructors said the main difference between the cheaper paints and the more expensive was a better match to new factory paints, and also perhaps more UV resistance, on a car I am reapainting completely, which, once done, will spend most of its life in a garage, I am not too worried about either of those. Lastly as an amateur painter doing it myself in the garage, I figure more steps is more chance to screw up, more chance for runs or bugs or dirt in the paint, so that was another reason I went single stage.
If you are paying somebody to do it it is really more about your preference on the looks and your budget, find a shop with the expertise and inclination to do it your way. As mentioned, most shops, especially ones that work mostly on new cars, will push a basecoat clearcoat, because that is what they do.
Lastly, the urethane enamel single stage is a very durable finish, much moreso than the old non-catalyzed acrylic enamels and lacquers.
I will add after my long narrative mostly supporting single stage that I have done some touch up work on my modern basecoat clearcoat cars in the last couple of years, I was skeptical about the claims of ease of blending and repairs with this system, but it does work pretty well.