it was said in the second post,
ar=accuracy ak=reliabilty
ar=small fast bullet ak=slower heavy bullet
if you want something for 100yard or under and just for fun, id go ak, bullets are really cheap, the gun is very simple for a new shooter and the good ones go for under 600$, if you want a top of the line ak go with a VEPR or a Saiga, but i would personally buy the vz58(vz2008) because they are lighter and cheaper and still accurate as the others, ak bullets have incredible penetration btw, they are just fun guns, slap a red dot on it and go to work or even just leave iron sights, remember thatthe predecessor of the ak is the SKS, also a great fun rifle that uses the same bullet as the ak 7,62x39
the ar15 is a little more advanced(alot more advanced mechanically) but is a great all-around gun, if you want something with a magnified scope and learn how to do any long distance shooting, ars are awesome for it, but they are more difficult to maintain, more prone to have problem, not they are not reliable guns, it just takes some learning on the shooters part, a GOOD ar will run you about 700 bare-bones, you will need to add optics on your own, i have always had both platforms but just sold the russian because after getting into the ars i never used the 762x39 anymore, but i am still glad i went russian for my first :TACTICOOL: rifle
the other good thing about an ak, you can sell it for pretty much what you paid for it, or more if you time it right
so get an ak type first, load up on cheap bullets, get the ar next year when your ready to get into more advanced shooting