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Not to get off the track about infusing, but you mentioned your final goal is to make ganache for filling chocolates. From my experience (and as others have suggested above) the only way to know how much flavor you will get, regardless of method, is to try it. Orange peel, for instance, has a very strong flavor that shows up even in a dark chocolate ganache. 

Surprisingly it is stronger even than grapefruit, which comes out as more subtle than one might expect. A little cinnamon goes a long way. Lavender can get too strong very fast, but it fades somewhat in a ganache. Ginger is quite subtle (unless you leave it in the ganache). Earl Grey tea is strong in an infusion, but fades in a ganache to the point where I have discovered some people can't taste it (unless they know it's there). I thought lemon verbena sounded promising, but the finished ganache had very little of the flavor, even though I used a lot of leaves. 

And as someone else stated, there is no getting around heating the medium (usually cream), and that causes some flavor loss, even some change in the flavor. I would also add that you need to try the infused cream in an actual ganache and then in an actual shell. I have given up on some flavors because they mostly disappear in a finished bonbon. White chocolate in the ganache causes the least loss of flavor, but you might be surprised (if you haven't already tried this) at how it overwhelms many flavors that seemed strong at first. Substituting a small amount of cocoa butter for some of the chocolate helps somewhat. A more dramatic way of flavoring a ganache is to use fruit purée instead of cream as the liquid; I have had success with that method using black currant and blackberry. There is another thread that is helpful about flavored ganaches.