I have heard of GlobalComix (which has gotten a good UI update recently it seems) but never any of the others. NoirCaesar doesn't seem to qualify as a "web fiction" platform if it's almost all paid and requires accounts, but maybe that'll change in the future because it does look nice.
Voyce.me I have never heard of despite being an entire year old. They have typos on their site, even their FAQ, which is never a good sign, but it's hard to say there. They're at least legit in that this comic God Game is marketed as an exclusive, and indeed the author links to voyce.me on his carrd page.
However, they are probably (EDIT: Eh I give it 50/50) inflating their viewcounts. 400,000 views for a single comic on a site that launched a year ago, with an Alexa score of 753,000? Very unlikely. 90 days ago it was rank #250,000, which is more impressive, but it's sunk a lot for reasons I don't know. They have a few other comics with giant viewcounts and not that much content, too.
Comparison: Here is one story (which I like) called Atk 0 Crit All. On Voyce.me, it has almost 9,000 views. In comparison, it has 335k views on Royal Road and 53k views on Honeyfeed, both proven sites that don't inflate viewcounts. Those are comparably much bigger, but keep in mind that Royal Road is in the top 24,000 sites, and Honeyfeed, while only around 490,000, has an ongoing contest partnership thing with MyAnimeList which has seen a huge boost in views there recently. Actually... this wasn't so evident when I looked at it again. The Originals with their huge 200k+ views make me suspicious, but not this one. I would delete this whole segment except it took too long to write lol
Voyce.me got a licensing deal for some webcomics a couple months ago, so it's definitely a viable platform, but it's a heck of a lot smaller than those top stories imply. Look at the Discover tab and you'll see.
As for Underlined, I don't know when it launched, but it's clearly marketing itself to young teens, basically a community hangout for creative kids rather than a place to share novels and gain readers. There's not many stories, a lot of them are spam, and they don't show views at all. There was another major publisher web fiction site like 10 years ago, and it shut down likely for the same reasons this one will; the major publishers are just clueless to how to make web fiction work, or else they'd already have created a Tapas/Wattpad/Royal Road competitor worth talking about.
Anyway, I have a big web fiction directory (also includes comics) of basically all platforms on the whole internet you can post stories on. I got to add two new sites today thanks to this thread, so there's probably more lurking out there I don't know about. Let me know if you find them.