BigWimm, you're going to find that opinions on broadheads are like opinions on what caliber is best for elk. Everybody has their favorites.
My advice. A good starting point (pun intended) is a broadhead that weighs between 100-125 grains. Get a good replaceable three or four blade head. By good I mean heads such as G5 Strykers, Rocky Mountain Ironhead, Slick Trick (Standards or Magnums), Magnus Stingers(lifetime guarentee on those) Trophy Taker's Shuttle T Loc, and as always the venerable old Muzzys. Some of my personal favorites are the G5 Montecs, Nap Hell Razor, Magnus Snuffer SS, and the Wensel Woodsman Elite. Those in the last list are all resharpenable and since I'm a cheap type of guy I like to be able to get more than one shot with a $10 broadhead.
My last piece of advice. Learn how to tune your bow and don't fall for the line of;" You need to get these mechanical heads. They fly just like your field points and it doesn't matter if your bow is tuned or not. Mechanical heads can work great, but I don't really like them for elk. There's a ton of guys that would dissagree with me but that's my personal opinion. I don't shoot enough kinetic energy with my current setup to make me feel like a mechanical head is my best choice. Good luck!