My experience with non-OEM camera batteries (from a variety of 'brands') versus OEM ones is:
1. Their usable/useful capacity is usually lower (by maybe 10-20%), irrespective of their nominal capacity as stated by the supplier.
2. The battery indicator accuracy (on the camera screen) is lower.
3. They have higher self-discharge rates (i.e. when they're charged but not being used).
4. Their useful life (number of charge/discharge cycles and age) is lower.
5. The capacity versus cost is way better, so you can buy two or three of them for the cost of one OEM battery.
Beyond the OEM battery included with a camera, I've nearly always bought 'mid-price range' non-OEM batteries (and usually I have three batteries per camera) as they are so much cheaper and I'm not using them day in, day out (or earning a living from them). If I was using them hard I'd buy OEM batteries, other than maybe having a couple of non-OEM ones as an emergency backup.
If I wanted good non-OEM batteries at a reasonable price, I'd probably go for suppliers with a decent reputation in the market to protect and that you might get some after-sales support from e.g. Small Rig, Neewer, Wasabi, Hahnel etc.