Verified answer

You would use "aber"

sondern means "but rather" or just "rather"

Der Himmel ist grau, aber es regnet nicht.

= simple "but" --> most often used

Ich mag kein Bier, sondern Wein. (I don't like beer, but (I like) wine)

= "but on the contrary"

--> to use "sondern", there must be a negation and a contrast or an opposite.

Hi, aber is what you would use normally, as in this sentance, whereas you would normally combine sondern with auch (meaning also) to mean but also, you would use this if you wanted to say not only..... but also e.g "Ich trinke nicht nur bier, sondern auch wein"

hope this helps! x