Generally you need twice the amount of fresh herbs as dried herbs for the same strength of flavour. The quality of the flavour of a fresh herb or spice can therefore not be compared to that of the dried version.
Herbs and spices get their smell and taste from the ethereal oils that naturally occur in them. These oils are very volatile, which is why herbs and spices are ground very carefully. No heat may be involved in the process, or the oils would all evaporate.
Just as with the grapes used in wine, the smell and taste of herbs and spices is strongly influenced by the soil in which they grew and by climate. This is why Muntok pepper tastes different from Sarawak pepper, and why Brazilian pepper again has a completely different smell and taste.
There are so many different herbs and spices that it seems a pity to limit yourself to just a few when preparing your meals. But do not let the herbs and spices dominate the flavour. These tasty ingredients should only compliment or finish-off your meal. Bon appétit.