There are about fifty thousand threads on this site dealing with 18 watters.
Reinhardt 18 gets my vote...full pure rich cleans up until about noon on the dial and then the amp just turns into a rock and roll beast...great overdriven tones...great touch sensitivity...power scaling is an option and it is really well implemented (and a bit different from the Badger--the drive and gain and scaling controls don't need to be kept in close proximity--the power and drive on the Badger sound best closely aligned)...both channels are great and I use all 4 inputs...one of my favorite amps ever! sounds great with a variety of cabs (have tried 1x12 with greenback, 1x12 with a Blue, 1x12 with a G12H30, and a 2x12 with a Blue and a G12H30) and I think it sounds great with single coils and humbuckers.
Suhr Badger 18 another great amp...love the cleans and edge of break-up tones (prefer the overdrive on the Reinhardt)...power scaling really effective on this amp as well...Pete Thorn demo is great and representative of the amp's tones...works really well with all my guitars and cabs.
For something more Voxy, the Top Hat Supreme 16 is an incredible amp through the whole spectrum of clean to mean...not quite 18 watts but close enough!