I tend to prefer rituals for bigger spells; but then, I mostly think of rituals in cases where I'm, say, planning E6. There's no way you can cast earthquake if you're not going past 6th level. But maybe you and a few buddies can cast it over the course of an hour.
That's the sense I tend to prefer rituals in, but it's also good for smaller spells; it doesn't chew up those combat resources, and it doesn't have the advantages over mundane methods like being a standard action instead of a minute to pick a lock.
I didn't like the 4th edition approach because every ritual cost money for each and every casting, which seemed to me like it would make it hard to justify using rituals regularly. If you have alarm, you want to use it nightly, but the costs add up pretty quickly.