With some herbs, it really doesn't make too much of a difference whether I used dried herbs or fresh ones. However, with some I have noticed that using them fresh makes a world of difference. In addition, herb plants tend to be more economical than buying bottles of dried herbs. I concentrated on the veggie garden this summer, but I'm planning to start an herb garden indoors this fall and winter. In the meantime, I buy fresh herbs as needed at the farmers' market.
When I get my herbs home, I find they keep fresh longer if I put them in water as shown here (note: you'll need to change your water at least once a day). Another storage method that works is wrapping them loosely in a light plastic bag and then storing them in the high humidity storage in my fridge. Old Target or grocery store bags work great for this!
So, which herbs are best used fresh?
Basil! - No question. I'll use dried basil in the occasional soup or casserole, but nothing comes close to the taste and smell of fresh basil. Dishes like Pizza Margarita or Caprese salad(basil, mozzarella & tomato)wouldn't be the same without it. Added bonus - fresh basil will make your kitchen smell heavenly!
Parsley - I've read cookbooks that proclaim no real difference between fresh and dried parsley, but I beg to differ and at least one other writer agrees with me. Dried parsley is something I use often. However, when I treat myself to some fresh parsley, I notice a pleasant difference. Fresh parsley has a certain green freshness to it that gets muted once it's dried. Also, if you're making a salad,you really need fresh parsley in order to get the taste and texture just right.
Cilantro - Cilantro is another one of those herbs that just does not bear much resemblance to its dried counterpart. The fresh herb has a distinct scent and adds a somewhat complex taste to your cooking. However, the dried version comes off a bit flat and can sometimes be bitter. This is one herb I almost never use dried. However, in its fresh form, it livens up all kinds of dishes and it's essential to a lot of Mexican cooking.
Rosemary - This herb is really more a matter of personal preference. Dried rosemary actually does a very good job in most dishes. For that reason, I'd say that having fresh rosemary on hand is not absolutely essential. However, if you can grow it, I'd go for it. I absolutely love the scent of fresh rosemary, so even though I use the dried version often (and will probably dry my own in future), fresh rosemary is worth using just for the scent.
Oregano - This is one of the few common herbs that I like better dried. Dried oregano(as long as it's fresh) adds great flavor to pasta sauces, pizza and other foods. I've used fresh oregano occasionally and I've read that various chefs swear by it, but have not noticed that it provides enough of a difference in taste for me to refuse the dried version.
Mint - Like basil and cilantro, this one is really best fresh. Dried mint makes good tea, and can be good in a few dishes. However, in salads, ice cream and sauces, fresh mint has a sweetness and bright quality that the dried stuff just can't touch.
Chives - Again, no comparison. Dried chives just don't do it. The fresh ones have a subtle green bite to them that is wholly lost in the dried version.
And those are just a few of the herbs I commonly use in my own cooking. If you commonly use other herbs and want to share some tips, I'd love to hear from you! And if you have any questions about various herbs, I'll try to help you as much as I can. And may all your cooking be flavorful!