Can't get Zappl to work so I can't comment on it. All I get is an empty timeline :/
What you mean "untagged" posts? without Tags micro-blogging would be pointless. Surely they will gets Tags to work at some point.
Regarding short posts/long posts....I only value and upvote information that I find useful/entertaining...not the effort.
I was a big Twitter user before the censorship started.
If on Twitter you only saw pointless posts/memes in your timeline you were following the wrong people or not using it correctly. I personally found a ton of valuable and worthy info on twitter...infact I had to reopen a twitter account recently just to keep updated on some critical info.
I'm very excited about Zappl and hope it can replace it.
Time is money...generally I prefer a post that gets straight to the point.
I plan to use Zappl (when it works properly) as main social media and Steemit just as Blogspot/Medium equivalent.
On Twitter you often get a link to a blog attached to a post...I think many Zappl posts will link to Steemit posts for further reading. A good synergy.
What people find valuable is subjective but I doubt in the long term mindless posts and overused memes will be raking in much rewards.
Even on twitter memes get old fast...and to get a meme trending you need to come up with something very creative these days.
Actually for memes I think there is even a Steem specialized app: Dmania...personally I never use it as I'm not into memes myself.
Steemit, Zappl, Steepshot, Dtube. DSound, Dmania etc we got all tastes covered...only problem most of them are not working properly.
That's the main issue with the Steem ecosystem so far: the apps ain't good enough or are facing major technical difficulties.