C3 is slightly brighter and smooths out low res content better. Not much different.
If you're not on a budget, then the A95L is the best TV out right now. Can't go wrong with any of the LGs though. Samsung S90C is the best value tv as it has the newest panel tech (QD-OLED), gets really bright, but is priced as low as the mid tier Sony and LG OLEDs. But Samsung looks the most unnatural, and there are issues with build quality and software.
If brightness and price is your priority go Samsung S90C.
If you want an all around experience at a solid price, go LG C2 or C3.
If you want the best TV period, then go Sony A95L.