I've been using Cat steel toe boots for years, but these ones are the best so far.

A nice flexible sole, makes kneeling easy, and the rubber toe cover means no more worn out leather & exposed steel.

Plenty of room, no pinch from the sides of the toe cap either, very comfortable.

The only drawback would be the eyelets for the laces - hey seem a little rough around the edges, so laces might wear out faster.

EDIT: February 2014.
The boots are still going strong, but I have worked out that waved laces are the way to go.