My foot is wide across the toes, and I have a hard time finding a steel toe with a cap wide enough to keep from feeling like my toes are getting cut off after standing in them all day. The best ones I've found for comfort for my situation were Doc Martens. They've got a nice wide, rounded toe cap and comfortable soles. Next best pair for comfort I had was a pair of Caterpillar branded boots. The docs are pricey, but the Caterpillars were just over fifty bucks at a local farm and ranch store. I think the Caterpillars have gone up in price since I bought mine, though. Both brands held up really well for me.
I like Redwings and Wolverine's when they don't have the steel toe, but I've never found a steel toed pair of either one of those brands that didn't hurt my toes.