I've only posted to them once, tagging the same post to each. Other than the sales pitch, I'm not sure what makes them unique, other than VYB has removed reputation and the downvote.
Unfortunately I've heard about some of the drama on POB and it concerns me. On top of that, the way POB sets up the feed, which is important for discovery doesn't seem very intuitive.
Having to scroll through two categories in an attempt to reach the recent posts section, then having to scroll to the bottom of the 1st 6 just to tap another option to find the whole feed is not efficient nor intuitive at all. I'm not enjoying POB when I check it out, so think Peakd is better. I don't see a reason to use POB, because it's not offering anything new and it's annoying to use.
VYB is more basic, but gives me more control over navigating to where I want to go. I like that, but literally every other frontend, but POB does that. I like that rep is scrapped and that they are looking for other options to moderate content.
For this reason I think VYB has more potential, but I can't say it's better, because we already have Blurt that functions similarly. Both use the same basic UI as well. Only time will tell if it will go anywhere. For morale it needs to get some updates out quickly though or it will seem as stalled as I've heard POB is.
Community involvement from the creators is important, so this is another benefit of VYB, but it's early and most leaders are usually more vocal in the beginning. That being said, it hasn't been enough at this point and communicating the plans for moderation and curation hasn't really happened platform wide, just a few passing comments on a post or two.
So, neither really offer anything to pull me to either one from Peakd at this point. It doesn't hurt to use their tags though, which is what I'll probably do. I'll be watching them closely and the one that strives for decentralization will get my attention.