I went thru the same dilema about a month ago, ended up with both and never looked back. the only issues I have with the 106 is that it made me want the same folding stock on my 105, and the trigger is not the usual ak feel, not worse, not better, just different.
the biggest thing that may sway your decision is that the 5.45 round is plentiful right now, but who knows in 6 months.
the 5.56 round will probably always be available, even if price puts it out of the reach of mere mortals, it will still be around. 5.45 all depends on overseas production and if its legal in the states.
recoil on the two rifles are almost identical, as well as fit and function (aside from the folder). I ended up buying a bunch of dedicated clear mags for the 106, but im told the 5.45 mags with a little bit of massaging work great, and those are cheap.
I also couldnt get the 106 out of my head as far as a must have, no idea why??? but I do have it and I really have no regrets about it. plus I can share ammo with my ar and my hk53