My wedding website is through The Knot, and I've had no issues! It's super easy to setup, guests were able to RSVP (and also could change their RSVP if needed) with no issues. I'd definitely recommend The Knot.
We tried out both and ended up going with the knot! We liked the styles a bit better as they fit our wedding esthetic, and it was super easy to navigate and setup!
Not sure if you’ve considered Mint.com, but that is what my friends and I have all used. It’s also a free platform, but what attracted me was that you can pay $16 for a year and make up your own URL. So it looks good on save the dates/invites and is easy for guests to find. It also has many of the same functions as The Knot, if not all the same.
We went with Zola and haven’t had any issues. I don’t like a lot of flowery or busy backgrounds with designs (especially since none of them truly fit our wedding style/decor/colors). But Zola had a simple black and white template that I liked. Also it’s easy to make changes from the app. However, we aren’t using them for registry since we only registered with Amazon.
I'm in the minority here but Zola is my favorite. I started making one at TheKnot.com but didn't like the layout. Zola's is really cute and I love the setup.
I looked at the knot but we went with Zola and I love it...the layouts are easy everything is in one place..idk may be just me but I wasn’t a fan of the knot
And Zola lets you order as many sample invitations or wedding invitations as your little heart desires idk if the knot does that I didn’t stay in long enough to see