As far as chain fast food burger joints are concerned in Las Vegas, I think Five Guys is hands down the winner. I have tried In and Out, Smash Burger, and Five Guys and they all have their strengths but if we are simply talking quality meat and quality burger...Five Guys all the way.
The menu is short and straight forward and you can add as many toppings as you like, no additional cost. I realize this place is more costly than In and Out but its in a different class and at least they HAVE bacon here. Bacon is a must.