Filters - get multi-coated, super multi-coated, digital multi-coated, or ?

I'm buying a new Canon 18-135 lens and will want a 67mm UV filter on it, looking at them ranging from $2 to $222 USD, am a bit confused as to how much I should spend.

I only buy multicoated name brand filters, saw Vivitar and Hoya brands, Hoya has:

glass $22
multi-coated $33
super multi-coated $47
DMC Pro-1 digital multi-coated $50
8 layer multi-coated $67

which one do I buy?