Prime glyphs have been designed by Blizzard to be no-brainers; they're powerful, and their purpose is clear. While there are four different prime glyphs that a holy paladin can choose from, most holy paladins will neglect the Glyph of Divine Favor and pick the other three. Some of the high-end paladins (such as Diamondtear) swear by the Divine Favor glyph, as they rely on their cooldowns heavily during the hardest heroic encounters. If you find yourself ignoring Word of Glory, you can sacrifice its glyph for Divine Favor as well.
Minor glyphs are largely irrelevant for us, as they only cut down the mana cost of spells that we normally cast while out of combat. It's cool to save mana, but the minor glyphs are really automatic and almost pointless. The major glyph situation is quite different for holy paladins. We have a smorgasbord of major glyphs to choose from, with each offering unique benefits. I find myself changing my major glyphs quite often, as many of them are only valuable in certain situations.