I have two Amazon Firesticks. One of them is the older version. Last fall I bought the newer version because it can be connected to the network via Ethernet (thinking that it would improve the data throughput). The older Firestick got relegated to the kids' TV in the back room.
Honestly I don't see too much difference in the two models as both seem to give me the same level of performance. However, I don't really tax them too much either.
The Firesticks consistently work fine with both Netflix and Amazon Prime. I also use the Plex app which works extremely well. Playon doesn't work as consistently as Netflix or Prime (according to the data throughput at the time of use), but I do get a lot of use out of that app--primarily using it to record, which it does fairly well. Hulu is even more fickle than Playon (but Hulu works fairly well when channeling it through Playon, especially when recording).
Unfortunately, I cannot get live streaming to work good at all (e.g. CNNgo, CBS News, etc.). I'm hoping that the live streaming works better when Viasat 2 comes on line. I also have an old Roku and live streaming doesn't work well on that either, so I can't necessarily chalk that up to a fault with the Firestick.