It really depends on the layout of the hand. Every hand is different and your clues to what he has are going to be different as well.
Specifically I would say it matters what type of hand it looks like you could have (as well as what you actually have), what type of hand it looks like he could have, and how you think he'll react to each of the different scenarios.
Generally I would say go for the check/raise bluffs when you think he could be betting a missed-draw or if you think he would value-bet thin, but then you can credibly rep a better hand.
Go for check/raises for value when you think he could be betting a missed-draw but wouldn't raise your bet, or when you have the best hand and you think your opponent either has a very good hand, or could be value-betting thin.
You want to bet for value when you think your opponent would be weary of a check raise bluff (like a missed drawy board when he has a hand that will beat missed draws but not the nuts)
Someone could probably make a good statement about when to do it at the bottom/top of your range, but overall this is pretty much a microcosm question of how to play poker.
The answer involves hand reading, understand the game flow/dynamics (how likely your opponent is to do something given how the past actions have gone and how he is likely to adapt) and probably some other stuff too