I think, streams are mostly for entertainment, but of course some are better than others. I think, there is more to learn from watching games, where all the hole cards are shown, to see how a variety of players approach certain spots. For instance on PokerStars Youtube channel there are regular streams of day 2 of Sunday Million or other big online events as well as from live events. These are games, where people play to win, rather than to entertain the audience.
Many are a waste of time (as far as learning much goes)... but there are some who are AMAZING!
Lately, watching some streamers has been a huge boost to my game. They are all relevant to what I personally play.
I sub to 1 cash game streamer & I also sub to 2 MTT players (both for over 1year... neither of them are popular names that people typically view).
THey are all winning players. (2 were the the winning'est' players in the formats they previously played in but currently are playing & streaming in different format but both are successful).
The ones I choose are the guys who a) I like b) are constantly sharing their thought process c) have hooked up with me off the tables, (via discord, messenger, emails, Fb friend now and have intentions of hooking up in person at some Live events and just when I'm travelling through that part of the country).
Also, I believe 'it depends' (< one of my favorite poker expressions) on how you view the stream(s). The ones I view I like to take a proactive approach where I am thinking about what I'm going to do in HERO's spot and why, (along with bet-sizing, etc. etc.). I've also been working on PKO's as they are still fairly new to me so while watching streamer & thinking through what their action will be, I also try to calculate on the go (on the fly.. in real time) if Calls are +ev (I am very accustomed to calculating ev & cEV on standard format tournaments but PKO's are different. After a bit of studying and learning method for calculating calls in them (ie. using Bounty Factor method... re: Dara's book) I put it into practice while viewing. I will also mark hands (screenshot) and spots I find interesting/difficult and then do work away from the tables on those hands.
All is helpful for building up one's intuitive thought process.
Many years ago (when I played MTT's) I would do the same thing when watching some of the vids. on Training sites (ie. PokerXfactor).
Which streamers do I watch?
Well I've thought about sharing this and it would help out the streamer to build their following but to be honest, I'm too selfish for this. I want them all to myself! I feel as if I've sort of fluked out onto finding these people... or perhaps it was meant to be?? (< I do strongly believe in this stuff).
My advice for newer players and watching twitch streamers.... find a winning player who likes to share their thought process. Find one who is playing at the same stakes as you are (or just slightly above). It can be a huge fail to watch some mid-stakes MTT player (or cash) and try to put it into practice on some $2 tournaments. It doesn't translate over too well and they will likely fall victim to FPS (Fancy Play Syndrome).
So unless they can find someone doing a challenge or something, moving up from the micros, it will often be a waste of time... time that could be spent much more wisely and efficiently.