We have the baby jogger city select. I really like our stroller. I'd definitely buy it again or recommend it to a friend. We have a 3.5 & 1.5 year old in it currently. My 3.5 year old is a bigger child, height and weight and she fits in it comfortably still. Now granted her head touches the canopy shade, but it doesn't bother her and she can still close it when she wants.
My only real complaint about it is that the stroller doesn't stand up when closed. My first stroller was a Graco travel system type and I liked that if I was taking it out of the car, it stood up while still closed. The Baby Jogger doesn't have that option, so it just has to lie on whatever ground you are on while you get the seats out and such. Not a deal breaker to me, but check it out next time you are at the store and you'll see what I mean.
We've flown with ours and it literally comes into pieces in a matter of a minute or two for easy travel (we gate checked it in it's travel bag. I have used it with the infant attachment and that was a breeze. I did have one issue making sure I had it in correct, I emailed them, they had me email a photo of what I had it set up like and then emailed me back right away with how to fix what I had done. Great customer service. I also like how the stroller can be configured into a number of different seating positions.
As baby #3 approaches, we are having to reconsider our different car seats for our van and family of 7, but our stroller is not something we've had to worry about needing something different.