Keep in mind, good paint poorly applied over a rough / poor substrate is no better than an economy paint applied over a well prepared undercoat.
I have used lots of alkyds, acrylic and urethane enamels over the years, but pretty much all I spray now is urethane single stage or base/clear.
To prep for base/clear is not a lot more work than single stage.
I have sprayed mostly RM-BASF finishes, but a small amount of Dupont as well. Over the years, I have used Miracryl, Limco 123 ( 1 - alkyd 2 - acrylic 3 - urethane ) HS-Solo ( rebranded to UNO-HD ) and Dia-mont base/clear.
The sky is the limit when it comes to paint materials. To fully refinish an extended cab complete in my neck of the woods with base clear ( including a quart of primer surfacer for repair work ) will run you $1500+ including masking materials ( tape, paper, ) and all other sundries. ( solvents, hardeners, abrasives, etc )
As far as lifespan goes, better materials will typically last longer, however too thick or too thin a film will result in less than optimum lifespan.