But I need some opinions.
When do you use one of these? are there specific maps or enemy you go one of these
But I need some opinions.
When do you use one of these? are there specific maps or enemy you go one of these
Starfall when you want to zone/wombo and they can’t blind you to negate your heals.
Shadowstalk in every other situation.
Starfall in 99% of the time.
Shadowstalk when they have a Fenix with salvo so you can deny the scan.
This is basically how pro Tyrande was played.
So why Shadowstalk was more popular, by a large margin?
Because people 
You know I meant tournaments? Shadowstalk completely dominates in tournaments. Pretty sure in ranked as well. Its go-to ult.
Just go rain of destruction roar
I think Starfall gets the old stigma of “OH the healer took the DPS ult /eyeroll” treatment.
I take Starfall more often than not, because casting it in a TF allows you to heal more often and do damage via Tyrande’s trait.
I know. Still, because people 
Starfall if you have a team that can work together to lock the enemy team down in it and somehow don’t have any other combos to use.
Shadowstalk at all other times. It’s just more generally useful.
Btw guys, Starfall is not good because “damage and combo potential”, Starfall is superior in anyway because of the CDR it provides to your Q.
With your AAs + Starfall/W/E hitting heroes, you can get instant resets on your Q (with 2 charges + 2 more cleanses), which heals more than shadowstalk by a mile. With the slow you can get easier AAs and stuns, plus you enable your team. Starfall also deals damage which helps with burst and is really good against certain objectives/fighting in the lane because the damage is done to all enemies. Starfall also has 10sec less cooldown than shadowstalk.
But well, if you want to heal your team by a little bit for 10 seconds instead of doing it much better with starfall, go for it.
Shadowstalk can be used to heal the whole team at once and possibly bail them out of trouble, Starfall is just there for extra Qs and damage. Shadowstalk is the more generally useful of the two or else every Division S team would pick Starfall like you suggest, which is especially notable considering how high a priority Tyrande is as a support right now.
Imagine trusting what division S teams pick omegaLUL
Imagine trusting a guy on a forum whose skill and knowledge isn’t verified on a competitive stage and can’t even BTTV emote right. OMEGALUL
So you’re a troll then, alright.
Starfall is great… for Qs and a bit of follow-up damage. But Qs cannot bail out a whole team taking damage all over the place from competent players. If your team is rolling over the enemies so hard that they can’t reasonably stop you, then sure, go Starfall. Otherwise go Shadowstalk. Shadowstalk has this wonderful quality called “global.” It can bail out a solo laner that’s in trouble while you’re all the way in bot if necessary.
Shadowstalk is strictly more generally useful for Tyrande’s role than Starfall. You must simply accept this, and move on. There are situations in which Starfall is better, but they are not the more frequent.
There’s no reason not to go Starfall nowadays.
More heals, check.
Damage, check.
CC, check.
BUT, if we are speaking about SL where everything works then yeah, can go shadowstalk. But for competent players Starfall is just better in every way.
I prefer shadowstalk on large maps where multiple spots can be contested and the team has heroes to split-contest objectives such as warhead junction.
AoE heals.
Ability to help allies outside your range.
Less mana draining than spamming Q.
Disengage potential by using stealth to negate attacks.
Starfall is strong, but treating it as the only option is just as shortsighted as blindly picking shadowstalk.
With a good starfall you will heal much more than shadowstalk and have a lot more benefits from it. Also shadowstalk heal is REALLY slow (over 10 seconds).
Why are they outside your range? That really shouldn’t happen.
“oh but I can help the solo laner”
First things first, why does he need help? Can’t he stay safe? Why is he overextending to get ganked like that.
Second, wasting a 90 seconds ult just to save someone on the other side of the map is really niche and even kinda bad. And you might not even save him because the heals are really slow.
Less mana draining but less heals, less utility, no burst damage, no CC… Also, 2-3 instant Qs heal more than shadowstalk for the whole duration.
Like I said, shadowstalk has it’s niche situations like getting stealth to deny the scan from Fenix’ salvo. But even then, you might be better with Starfall.
Definitely not the only option, but definitely better 99% of the time.