I liked the Clifton 2 better than the 1 because the tongue in the 1 was too thin. I didn't mind the extra weight in the 2 due to a padded tongue. It was nice the top of my foot under the laces didn't get sore anymore. Both were a bit narrow in the forefoot for my feet and I'd sometimes get blisters on my pinky toes on long runs.
I liked the Clifton 3 better than the 2 even though it weighed more because it was wider in the forefoot and I appreciated this on the long runs and during ultras( I wear the Cliftons on trails since I run mostly on hard dirt packed trails in Southern California).
One thing I hated about the Clifton 1,2,3 was that they softness and squish deteriorated really fast. This is what I like about them so much. Usually after 150-200 miles the soft feeling I loved was gone. I would wear them to 350-400 miles even though I didn't enjoy them much the second half of their life. I would stock up on them when they went on clearance as paying full price seems like a ripoff for their short lifespan. At $80 dollars a pair I feel like I was getting a decent deal.
The Clifton 4 isn't as soft as the previous versions but it's midsole is much more durable. That being said, it feelslike a standard trainer now. Medium weight and well cushioned. Durable. I like it but after I wear out the 3 pairs I have waiting in the wings, I might consider buying another everyday trainer like the Pegasus, Ghost, Ride, etc. Depends on what has the best clearance deal at the time.
Current rotation is the Clifton for everyday runs, Clayton 2 for harder runs, and an old pair on Stinsons with 600 miles on them for days when I can only manage a shuffle.