April is too far away.
there is Mobile world congress coming out, that will release new phones (not a new Galaxy though) and that will drive the price of older handsets down.
the phones you are looking to compare is:
a midrange Samsung, where the Samsung bloatware will bog up the phone's ram, and make doing average tasks take forever.
compared to a lite version of the flagship from 2015
so the base tech you are comparing against each other is 2 to 3 years old in both cases. this means there will be no OS updates, and that means everyday apps will start lagging as they are built for newer hardware, and newer OS.
if April comes around, and these two are still the only options in your price range, I would say go for the P8.
that being said, rather look at the other Chineese phones like Xiaomi