Yeah right, that's what I use too,
but what if Op doesn't use Cubendo..

 

youlean

 

Prism is really great AND gentle with your eyes.

I noticed this post lacks a few quite known metering plugins :

Span plus by Voxengo has been one of the most if the most popular metering plugin for spectrum for years and still is very good.
Span plus works like Prism with multiple instances.
They have free frequency dependant correlometer too that is cool.

https://www.voxengo.com/product/correlometer/

And the Bluecat audio metering suite is really awesome.
They have free stuff but their paid stuff is the real deal. I use a version from AZ that works well since years.
What is cool with Bluecat is that their metering suite is quite detailed.
They have a classic free spectrum viewer.
Others are multi instances/comparative spectral analysis with more instances at the same time than Prism. The same with a multi stereoscope and a multi oscilloscope.
Stereoscope and spectral analysis also have a 3d displaying version called "pro" (but that are not multi instances)

https://www.bluecataudio.com/Products/Category_Analysis/

They also have a meter suite thing
https://www.bluecataudio.com/Products/Product_DPeakMeterPro/

I don't know why you don't want to go for NI stuff but if you use AZ material you have all plugin alliance by r2r there. And on the last version each installer is separated so you can install ADPTR metric ab only if you want...
Metric ab is really hard to beat in terms of all in one metering tool imo.