I'd have to say my Sony VPL-VW50 "Pearl"
Just ~3 years ago, the thought of having 1080p resolution and anything more than ~1000-2000 CR for less than several tens of thousands of dollars seemed like a dream.
Then Sony blew the doors off of things with the Ruby. We all of the sudden had $30K+ performance for $10K.
A year later along comes the Pearl. Performance on par or better than the Ruby, yet listing for half, and streeting for even less.
In the space of a year or so, those 2 machines changed what had been a somewhat static linear projector price/performance curve radically. We know have numerous relatively inexpensive 1080p units with excellent CR to choose from.
I had one of the first Pearls in the country (# 4 I believe), and it's been the stellar centerpiece of my theater.
While no tech is perfect, mine has dead-on convergence, and has a lumen spec that's actuality based on reality. I'd like a little better lamp life, but hey...