I obsessively compared websites before choosing, and ended up going with The Knot. Here are my pros/cons:
Zola – Honestly I just didn’t like their templates. I also wanted to include a more traditional registry for older folks, and I’ve heard that can get lost on Zola’s site
WithJoy – I looked into this after a ton of people recommended it. I like that you can add multiple questions to your online RSVP, and when a person RSVPs they can see online exactly who is in their party. Their RSVP spreadsheet manager is pretty cool, but I didn’t really need that much functionality. You can also add a ton of FAQs. There are two layouts – more traditional with pages, and more modern where everything is on one page and you scroll down for info. I did not like that only some “theme” options worked for the more traditional layout, and with both layouts trying to upload and get a photo to look right was a pain in the butt. You also can change the names of the pages, but you cannot add pages. I liked that the registry buttons were the logos of the stores, so it just looked clean and cute. I did not like the look or organization of the “travel” tab listing accommodations and things to do in the city – it was just generally ugly, but did include buttons for contacting the hotels. Can password protect.
Minted – I thought the options for theme were SO pretty. They also have a good RSVP system (letting you do multiple event rsvps, and showing a specific number of members in a party), although the way it shows up for the admin when you enter people’s names is a little weird. Also you can’t customize anything without paying a fee (although you can do a custom URL, it just has to have “minted” in it). The pages in general looked a little plain (no photos, all text, and no real variation in the text since you can’t customize it). Can’t password protect without a fee.
Weddingwire – Just in general seemed inferior to the others. I didn’t look into it much.
The Knot – The biggest complaint I have about the knot are the “themes”. There aren’t a ton of choices, and the layout of the theme is not customizable at all, other than font style and color. Other than that, you can add or remove pages and sections, customize the names of pages, integrate your hashtag with their photos page, allow multiple event RSVPs, RSVP options for food, password protect certain pages, and when guests RSVP they know exactly who is in their party. If you have a Zola registry, because it is a competitor, the button for the Zola registry on the Knot’s site looks a little weird, but that wasn’t a huge deal to me.
Hope this helps! I’m sure I forgot some things…