We bought the B-Agile in anticipation of our Dec WDW trip. My son is 2.5, but he is 40 inches tall. I needed something with a high weight limit and that would fit his tall frame. Both the City Mini & the B-Agile fit the bill. I went to Babies R Us and tried them both.
The B-Agile won out because I felt that it was easier to fold, there is not a bar in the back so it is a bit better for parents with long legs, the basket was easier to use, and it was cheaper.
So far we have used it on rough concrete, fairly high wet grass, and indoors on carpet and it has performed wonderfully.
I bought mine on Ebay. It was new in box, but it must have been a return or dented box item. I paid less than $140 for it. Unfortunately I was not able to get the pretty Peacock blue that I wanted, but for $60 in savings I am not complaining.