For sure, if you want nappies to last, then fitteds will last longer I think. I had some MEOS that were second hand for Charlotte and then went on to be used on Ben and they still had loads and loads of life left when we sold them on. But we do have some BGs, Green Kids, Happy Heinys, and Blueberries which are going strong on Ben having been used on Charlotte.
As Steph says, the BGs have probably faired the worst but not in terms of pul or elastic but the velcro is not as sticky and looks really tatty. Cotton laminated pul tends not to wear well, it does stiff and tends to wear at the edges I have found.
In fact, the nappies that get used and abused most often at the moment are the Coolababies as they are used at nursery and they are still looking really good and are working fantastically. So considering they are so cheap, they have been well worth the money.