AMD seems to be easier to upgrade while keeping the pc together for the most part. Some AM2 boards could support the 45nm (K10) CPUs in later BIOS revisions. With DDR4 being implemented with Ryzen it won't be possible to do that from the last gen. get the best GPU you can afford. If it is bound heavily by the CPU or not, the bigger, better GPU that you get the more performance you will generally see. Get the better CPU when you can.
Buying a graphics card to match that of an Athlon ii 250 is interesting idea in that of you can build a PC with parts from the athlon ii era for pretty cheap. And later on you can make one of the videos titled, "Gaming PC from 2010, Can it hold up today?" or some such flippery.