I also realized recently how much I like just hearing the sounds of the table and no talking, when watching those corey vs. earl clips on youtube. It can be refreshing.
It's also great to hear players, especially if they're having a bit of a discussion

(johnny to earl: "when I'm shooting, you shut up.")
Commentary, when done well, is nice. I especially like player reviews because you can see the thought process and also see how they'd revise their choices if they could do them again.
The route prediction stuff is boring and probably should be avoided in a connect-the-dots 9b rack, but it can be interesting in funky situations or in less obvious games like 1-pocket or straight pool.
I definitely have a pet peeve about hearing eating sounds but it happens so rarely that I can't complain too much. I would just ask that the commentators take their break and eat and let the viewers enjoy 15 mins of silence if we're doing a live stream. There doesn't have to be nonstop talking (especially at 3 or 4 am).
I have mixed feelings about Danny D... I loved his golf ball story but wouldn't necessarily want to hear it during the finals of an important tournament. He has some funny sayings but I found he can be overly negative and border on being disrespectful to the shooter. He's very critical when he doesn't agree with a shot selection. "No no no, playing that 3 rails with draw is totally the wrong shot. The guy just 3 railed his wallet. There's no reason to do what he just did. This is simple."
I like when a commentator is not afraid to let some color slip in there and will offer controversial opinions rather than being super careful in everything they say... as long as it's not directly insulting to anyone. Or, it can be insulting in a joking way where the 'victim' could laugh with it. I like hearing accents and off-the-wall phrasing. I wouldn't mind a little blue language now and then too. Some of the best commentary I heard was when grady let it all hang out on the accustats "X-rated language" video.