I'm a big STOS fan for big game. Took bison and elk with them. Heavy, hard, hold an edge. Alaska bowhuntings heads are great, but you have to remortgage your house to get them. Grizzlies are great, Zwickey, Magnus, etc....all super heads.
With big, dangerous game,Keep to the two blade my friend! Others, go ahead and argue all you want....but a two blade will out penetrate a three blade when hitting anything hard. Less friction, less surface area to slip through and/or past bone. Plain and simple. Not that three blade heads are bad, they are fantastic. But pure science...the two blade of the same weight, force and sharpness will penetrate better.
Oh boy, THATS probably going to start a battle.
Good luck with the moose, Shoot as heavy a setup as you can. A heavy head, arrow is mandatory. I know plenty of guys have killed this or that with a lighter bow/ arrow combo, as have I, but with them big critters you just never know whats gonna happen. Hit 'em as hard and heavy as you can, then get the heck out of the way!