I've got nothing against PHP, it's just a matter of preference. There are a lot of fantastic apps built using PHP and I use them on a frequent basis. However, if I build something, it's Ruby all the way. I just find it much cleaner and pleasurable to develop with. Looking at PHP makes my eyes hurt now.

The great thing about PHP is that the difficult problems have mostly been worked out. Getting a PHP site up and running and scalable is standard stuff.