The newest business class seats are only available on about 5 planes out of >130 in the fleet (I don't know the exact figures but that's the ballpark).

In the pre 11/16 business class (Nov 2016 when it was introduced) there are various "generations". They're all broadly equivalent, the main difference being quality of IFE and the handheld controller, which in the newer versions is wireless and thin like an iPad while in the older ones it weighs the equivalent of a small rhino baby and is connected with a cable. The oldest version also doesn't have touch screen I believe but not sure on that.

Service wise it's all the same, recline wise as well. Also the oldest planes are often the first to be retrofitted with upgraded seats and IFE if they've been in for a major overhaul, the planes you want to be avoiding are the 4-5 year old ones. Also the newest ones are unlikely to have Wifi as Wifi in the 777s is installed after aircraft delivery.