We've used these Ovonic batteries commercially for years now and they have yet to let us down. After a while they do get a bit puffy, but that's after a lot of charge cycles with plugging the batteries into the charger right after every flight, charging on 1 amp. This is usually the moment we replace the batteries for a new batch. They deliver excellent power throughout the whole flight. Beware though that the batteries sag really fast when they are getting empty.
We have tested multiple brands for these types of batteries like CNHL or Tattu, but found no real difference in performance compared to these Ovonic batteries.
All this at a really good price makes these Ovonic's an absolute steal.