As far as the best, I am not sure. Alot of good stuff LED wise has come out the last couple years. As far as buying lights, I go Lowes, Home Depot, or Menards. I started buying lights the end of October because most of the stores, once they run out, they do not restock. Good luck on your hunt!!!!
I bought LED lights at Sam's Club, 50 lights on a string.
The pros: reduces your energy bill and can connect up to 46 strands on one single outlet, where as my old Christmas lights I could connect only 3 to an outlet (any more would cause a blowout); plastic bulbs in comparison to glass bulbs.
The Cons: Not as bright or as decedent regular Christmas lights.