Either size should be a considerable increase in comfort from a 700x23 which I no longer ride. My current tires are 32 cross tires which are dying. I may go for a set of 30's with the round/smooth profile rather than the 32's with cross treads. Keep in mind manufacturers aren't always on the same scale when it comes to measurement; I've seen 32's close to 30's and 28's also close to 30's in actual size.