Among the old masters, Michelangelo, Rembrandt, Botticelli, & Rubens are my favorites. If asked who I believed was the greatest artist of all time, I would go with Michelangelo followed by Rembrandt. I obviously can't draw or paint as well as Michelangelo... but I understand his methods... I know how to draw "like" him. Rembrandt on the other hand? I wouldn't know where to begin. I understand the linear elements of Michelangelo and how he suggests sculptural form... how he uses color. But Rembrandt's paintings are built up of this great variety of textures... impasto, scumbling, ala prima, and glazes combined directly in a intuitive manner that I could not even begin to emulate any more than I might emulate Michelangelo's sculpture.
When it comes to our artistic heroes I wonder how often we are attracted to artists who work in a manner similar to our own work. I love J.M.W. Turner... but he's a landscape painter. I can't do anything with him. As much as I admire Monet, Corot, Pissarro, Constable, Bierstadt, etc... I don't tend to look at them a whole lot because they don't offer me much I can use in my work. On the other hand... I've gotten ideas from fashion design, wallpaper, architecture, and other sources.