i'm with Raz, had air, fitted a fair few kits too but there's always a risk of something going wrong, fuse pops, relay dead, freezing lines in the winter, bags perishing, etc etc
i had top quality stuff with e-level and would occasionally wig out as all electronics do once in a while, my favourite was when it decided to air out the front drivers wheel sending the subframe into the floor and wheel into the arch at 70mph
i like to drive my car hard and with air there's always that concern in the back of your mind that it's far more prone to failure than any other suspension and if it was you'd be in trouble.
maybe i'm too old i don't know, for a show car i'd run air again, anything else - no, i like to get in my car in the morning and turn the key and drive off knowing my suspension works
also be prepared to wear all suspension bushes out twice as fast and tyres as you're tracking will never be 100%
the air game is moving on though and coming down in price which will hopefully mean quality / new ways of doing it will be introduced, it's all a bit 'it'll do' when it comes down to it.