Collections are finicky things, there is always something elusive you want or desire.
That being said, despite many things not yet a part of my collection, I can safely say that one Toyline is actually complete.
Not counting the Pepsi Prime, Botcon Set or Masterpiece Starscream, because I consider them secondary items from the line, my Mainline Retail Classics Collection or just Transformers 2007 if you prefer, is 100% Complete.
Mini-Con Teams, 6/6
Legends Class 7/7
Deluxe Class 8/8
Voyager Class 3/3
Two-Packs 2/2
Combiner Team Exclusive 1/1
Ironically enough Grimlock was the last figure I purchased/needed to complete my collection and I got him from TRU.CA.
The first Classics Figure I bought... Well it was either Starscream, Bumblebee or Rodimus, possibly even two of those three at the same time. I can't recall exactly.
I'm very close to completing the Generations Sub-Line from 2010-2011 as well, or at least being up-to-date with it. Out of 17 deluxes I only need 11, but since half that number hasn't even hit Canadian Retail yet my actual needs are 5 WFC deluxes and one Classicsverse deluxe to go. Which would bring my total up to 12/17 (Not counting Junkheap and Sky Shadow as they were only recently announced and so I haven't included them in the total of Generations Deluxes available.
I find it rather ironic however that so many toylines have a set number of desireable figures and then repaint hell comes along. Which is why I will never own 100% of the movie toylines as I don't want nor need an army of Bumblebees.