VRAM is not that important. The primary advantage to the Quadro is unlimited access to nvenc. So you must ask yourself, how many encoders are required by my typical production?

In general, the RTX2080 is a substantially more powerful GPU. Passmark reports it as over 50% more capable than the Quadro P5200.

https://www.videocardben...orce-RTX-2080/3888vs3989

Both are reasonably current hardware, so very capable. I suspect you're better off with the RTX based system.

Remember, in many cases, if pressed you can offload some of the encoding to another computer. Take program out via NDI to another system. That system could be very simple since its function is limited.

If you want a good combination, 9900k plus p5200.
All people speak about nvenc but custom edid is my favorite thing about quadro cards.
If you use hdmi output for live imag, custom edid is a must. Basically you can change a cable or add a second output without need to restart nothing.