Humbuckers are great for a heavy sound with minimal effort, or for sweet thick leads and I think they are great
But.....
single coils all the way for me, I find more personality shines through and that there's more dynamic range, you have to really attack a good tele bridge to make it sing; humbuckers, particularily high powered ones seem to do all the work for you, they can break up too easy and encourage you to play too generic. That depends on ther player though, in the right hands (Peter Green, BB king, Jimmy Page etc) there's no deniying how good they can sound.
But it's the other way round Dave, single coils for when you are young and agressive and the buckers for when your older AND MELLOWER and your fingers need 15K output of assistance :D