The prior threads addressing this basic issue appear to be older.

Seems that for NinjaTrader 8 (NT8) the options that make the most sense are CQG (the default), Rithmic, IQ and Kinetick

Is there a reason to choose one or the other? It seems that obviously IQ and Kinetick are much more expensive monthly subscriptions but also offer news, market internals.....

Looking forward to hearing peoples opinion on this.

I have been an iqfeed customer for almost 4 years. Never had a down day, except a couple of hours during a high-volatility day a couple of years ago when some of the symbols were delayed by a few minutes. iqfeed was extremely apologetic about this issue.

You can customize your package to your needs, and if you commit to annual billing or payment in advance you can get a decent discount.

Kinetick is an iqfeed clone (as far as I can tell).

You need to answer for yourself if you actually need such a data feed. If you just want to stare at charts, you can get Interactive Brokers or TD Ameritrade Think or Swim which offer real-time data and charting FOR FREE. NinjaTrader can utilize their data feeds too.

I pay for iqfeed, because I download the data for analysis in R/Python all the way to tick level. There are 'free' options (mainly for daily data), but sometimes they stop working and/or their data is inaccurate.

If you want to use Ninjatrader with a brokerage you use CQG or Rithmic through their brokerage like you say. Rithmic has the advantage of full orderbook depth. I remember seeing a video a while ago where FT71 was saying he mas changing from his current data provider over to Rithmic to use with Bookmap for the full depth.
If you want to pay extra for data, or use the platform with a data feed but are not using their brokerage, IMO use Kinetick. It is a discounted version of the IGFeed, same data but cheaper as it will work only with the Ninjatrader platform.
If you need the extra data for another platform as well, then get IQFeed as that will work with almost any platform, and the data is downloaded on to your computer and then can be used by multiple platforms concurrently.