Some comments here are true.
I'm not a hardcore gamer (I only emule old consoles sometimes lol), but I'm an Android fan and I've been for a long time, even better if it's pure/vanilla Android. That's why I hate custom UIs like ColorOS, MIUI, EMUI, One UI, you name it.
Development is also one of my concerns when getting a new phone, I stay away from phones that make hard to unlock bootloader, rooting or installing custom ROMs (I killed a Xperia X8 once trying to unlock the bootloader... lesson learned!).
So, when it's about OnePlus, I have mixed feelings. I lived glorious times with devices like OP2, 3T, 5T, 7 pro, they were awesome and OxygenOS was freaking great. Unlocking the bootloader was so easy and it still is, so when we talk about unofficial development, let's say that OP is still making it easy.
In the other hand, I don't like the path OP is taking. They say it's a company "run by fans", but that's certainly not true, because they are just adopting what OPPO does, mainly for the software. As I said, I hate heavily customized UIs or UIs that intend to be iOS copies. The main reason I don't use an iPhone is because I hate that horrible OS. I understand why Chinese brands want to mimic iPhones, I just can't deal with that.
So, if you are interested in development, installing custom ROMs, etc., OnePlus is still a great choice if you have time and patience to read and follow instructions for procedures like unlocking the bootloader; otherwise, if you want to get the best of Android without having to deal with actions like installing a custom ROM, just stay away from OP, there are better options.
If you are into hardcore gaming, photography, video editing, etc., OP is always a step behind from other brands, to be honest. Even if the phone has awesome hardware, the official software is very crappy.
At the end, it's your choice!