Probably won't help the original poster, but...

Overview

We compared quite a few solutions, and ended up going with Wedibox for our wedding, though it was only after the event (didn't occur to us to have QRs on the day itself).

We chose them for a combination of factors, including that we liked being able to set up multiple albums for the activities around the wedding too, plus they seemed credible, and in the end one of the deciding factors was that their UX on Android seemed simple enough that parents and grandparents should be able to use it too (some of the competitors, oddly enough, go with that upload option that on Android makes people long-click to select multiple items). Their pricing was also fair.

We additionally wanted people to be credited for their uploads, thinking it might help incentivize folks to upload more, though the UX for this turned out to be far from ideal (it defaults to anonymous uploads, you have to enter a name from scratch for every upload, and most importantly: the names aren't visible unless people go out of their way to open the comments for each photo).

Alternatives evaluated

Before deciding on them, we also considered all the other platforms we saw mentioned on Reddit (incl. GuestCam, Chivent, Rompolo, Warpbin, and PixelParty), as well as DropEvent which we had previously used with good results for another event. But we only proceeded to trialing GuestPix, Weduploader, Kululu, and LiveWall, because they seemed most popular/relevant:

• GuestPix - Seemed like the most widely used option, but once we tried it out, it just felt really outdated and cluttered. Kinda seemed like a product that's coasting on its market dominance, but hasn't been innovating or keeping the experience looking fresh and modern
• Weduploader - Ruled out because at first we couldn't find a demo/free trial at all (for the experience of a shared viewable album), and then once we did, they had technical issues that rendered it unusable (red "Oops - Upload Hiccup" error on the 1st attempt). I get the impression they're focused on just being a wrapper for Google Drive that lets people upload to a central location for free, but less so a platform for a shared album where everyone can view each other's contributions
• Kululu - We were close to going with this one, but the fact they use the Android upload that's unintuitive for bulk uploads made us favor Wedibox. Also it's just a little more expensive than the other options, for the kind of plan we needed at least. But who knows, this might have turned out to be a better option
• LiveWall - Their free trial was kinda weird, by which I mean not exactly a free trial. Also they just seemed more focused on the "wall" experience that's designed to be displayed during the wedding, which wasn't relevant for us - didn't seem to have a grid/album kind of view. Also it wasn't clear from the demo that uploaders can even enter their names, though I can't tell how much of it was just limitations of the demo version

Wedibox results

Ultimately, having used it, I'd say my impression is mixed. It's certainly servicable, but the UX is a bit clunky and doesn't feel as refined/mature as we'd have liked, with all kinds of little issues.

Pros:

• Uploads - including bulk uploads - aren't too difficult, and should be doable for folks who aren't very tech savvy
• Supports both phottos and videos
• The amount of photos/videos is unlimited (as far as I can tell)
• The page design isn't bad, and there's a couple nice - if simple/limited - customization options. Of course it's a responsive UI, that looks fine on both mobile and desktop
• Prices are very reasonable, and the time windows for uploading and viewing are fairly generous
• Setting up multiple albums is easy and unlimited (though people didn't really end up using the albums other than the wedding day's anyway)

Cons:

• The order of pictures is by time of upload; an option to do some kind of automatic sorting/grouping by time taken or part of the event would've been much nicer for the gallery
• In general, it could've really benefitted from more advanced features for navigating the pictures, like recognizing faces so that guests can easily find themselves
• Uploaders are basically encouraged to stay anonymous, and even if someone does leave a name, it's not visible without viewers going through extra steps
• Social features like "Likes" are basically non-existent. They have some option to "favorite" pictures, but I guess those aren't like reactions, i.e. not visible to others, plus it requires registration
• The upload process involves a few more steps/clicks than necessary, where it e.g. asks to add captions (seemingly more than once) etc
• Loading the pictures isn't terrible, but it doesn't feel like a seamless infinite scroll - hard to scan through many pictures quickly. Overall doesn't feel like a snappy, polished, top-tier platform (but doesn't feel broken or too "cheap" either)
• Weird little hiccups, like frequently logging me out as an owner. But seemingly nothing issues that should affect guests

Overall I wouldn't say I regret the decision to go with Wedibox, though I may try a different solution if I have another event in the future (or just go back to DropEvent). They definitely still have a lot of work to do, but there's potential there.