Studs give the most all around trackion. On icy surfaces larger lugs actually DECREASE traction. If you are a trail rider I would definately say go for studs.
I have 120 on my Zr 500 and they give a lot of traction on icy turns and hard packed snow.
If however you are into heavy powder riding, that is when large lugs come into play.
Sometimes a good compromise for both worlds is to get a 1&1/4" track and stud that.