I currently own one of each. I have a Vector AK-47 (my 3rd AK-47) and an Arsenal SGL31-61 (my second AK-74). Personally, I greatly prefer the Arsenal. It is just a beautiful gun in fit and function (and it damn well should be at the just shy of $900 I paid for it). The Vector is put together very well also, but I just haven't found an AK-47 that feels good to shoot. It just kind of slaps you around a bit. Not badly enough to really say it's a shoulder buster or anything crazy like that. Just it isn't that fun to put a large number of rounds through it, at least not as fun as my DPMS AR or my Arsenal 74.
The mag thing is kind of annoying. My Arsenal shipped with a little puny 10 rounder. I had kept 3 of the Bulgarian AK-74 mags when I sold my CAI AK-74. TAPCO does make mags currently. If no other surplus mags show up on the market, I'll probably just buy some of the TAPCO mags (maybe in Russian Orange). The TAPCO mags for my Galil work great and they are a fraction of the price of the original 35 round steel mags.
Another vote for the 74. I have a "cheaper" version if you will, Tantal Sporter. Paid less than $500 for it, came with 2 tight fitting 30 round steel mags. Bought 4 tapco bakelite orange plastic mags that function fine for me. Ammo is half the price of 7.62 if you buy the surplus stuff. I personally like the accuracy and recoil of the 74 better than the 47. I don't plan on owning anymore 47's ever, owned 2 of them and sold them both off. The 74 will be around for awhile. My only complaint would be the cheezy plum upper handguard that fits the Tantal only, would like to do something about that later on.