Apparently I asked too soon. Summarizing my recent findings, I conclude that **adrenaline** is the better term.
To be more explicit, here is why:
* The US National Library of Medicine recommends “epinephrine”, this is however mainly due to historical reasons (adrenaline used to be a trademark name in the USA).
* This quite comprehensive paper on the issue presents a series of arguments for the use of “adrenaline”. These include: Better compatibility with other languages (where epinephrine is not at all in use); Better integration with other biological terms (adrenergic receptors, adrenal gland, adrenectomy, etc.); Better historical accuracy (epinephrine used to be the name for a neurochemically inactive crude extract from the adrenal glands).
I find the arguments of the referenced publication convincing, though I would recomend you read them in full.