I'm assuming your on a PC-if you are on a Mac-The Illustrator is the way to go, since Corel is dumping thier Mac version-
To me they are tools, one is no better than the other, if money is tight, I would go Corel, solid program, lots of support in the sign community.
I use Illustrator with CadTools myself, started with Corel, but switched when companies I worked for used it, IMO it's more intuative. Either way-you can't go wrong.