I see this posted constantly on Facebook groups, people asking in forums and I get asked via social media.
The answer of course is a 14-200mm macro f/1.4 with image stabilisation and so many elements to create amazing bokeh that you'd lose count.
Unfortunately that lens doesn't exist and if it did it'd probably be about the size of a horse!
I don't honestly know who's asking this but I wish they'd stop it.
The real answer is of course there is no such thing as a 'best lens' for a photography genre that's as wide as wedding photography. If you want a quick and dirty answer then the closest thing to it would probably be a 24-70mm f/2.8 but like anything that is good at a range of things, it rarely excels at any of them.
Don't misunderstand me, I used a 24-70 for many years and loved it's versatility but did I love the images it produced? Meh, sometimes. I think the only time I genuinely loved that lens was during the evening reception, specifically the dancing. Most 24-70mm lenses have snappy AF and obviously give you the option to zoom. Plus it's probably fair to say that the lighting in the evening means you're not overly worried about perfect tones etc
I didn't use it for portraits because I had a 50mm f/1.4 art from Sigma that did a much better job, or I'd use a 70-200mm f/2.8 because it could separate a subject from virtually any background. I didn't use it for macro or details in general because it just didn't render small details well enough.
I think the question itself is a red herring.
You can reasonably ask what's the best lens for macro photography or what's the best lens for astrophotography, maybe even what's the best lens for portrait photography though that last one is a bit trickier. All of those genre's are reasonably specific so you can fairly easily narrow down the options. Portrait is a stretch because frankly you can take a portrait with almost any lens, but there is accepted wisdom that for portraits (in the traditional sense of the word) a longer focal range rather than the wider is more flattering.
For wedding photography it's not so easy. Instead of 'what's the best lens for wedding photography' I think the question should be 'what lenses do I need for wedding photography?' that's easy enough to answer and might not be as long a list as you'd expect.
Here's what I would recommend to someone starting out....
It won't be perfect. There'll be times you'll wish you had something wider and something longer but you absolutely can do a great job with just those lenses.
135mm f/1.8 (or f/2)
This is pretty much where I was about 18 months ago and mostly happy with it. You've got good reach with the 135mm and if you're shooting mirrorless and have a high megapixel camera, you can switch to crop mode and boom, you're at ~200mm. The macro adapter will let you get detail shots that are better than you could without and are a cheap option. If you go down the holy trinity path then you have fantastic versatility at the expense of some light which should only be a possible issue in a very dark church or other ceremony room.
90 or 100mm macro
This is me now. The 85mm f/1.8 Sony FE is a fantastic lens and honestly one of the few genuine bargains in glass out there. It's light (and I mean lightweight!), fast focusing and sharp. I know the Samyang f/1.4 gets good reviews and it's cheaper than the Sony f/1.8 but personally if it's the first lens you're buying with any camera system, I'd buy a native lens rather than a third party. I eventually stumped up the money for the GMaster f/1.4 version because of the sheer quality of the images I'd seen online. It's ability to turn the background to butter seemed worth it and I don't regret the purchase. It's a noisy lens though, be prepared for that.
I also felt the 35mm was restricting me. I had the Sigma f/1.4 version and honestly, I love that lens. It was just I couldn't get back far enough on occasion with it so wanted something wider. The Sony 24mm f/1.4 GM is an astonishing lens, incredible quick AF and sharp as a tack. It's also lighter than the Sigma. I'm hoping to use it for astrophotography in the next year as well since with such a wide aperture it should be very capable.
135 & the macro are for the same reasons as you'd expect. I usually break out the 135 during a wedding if the church is huge or if there's mingling time and the sun is shining. I always use it during speeches. Macro is what macro does, no surprises there.
The 55mm was so I had an alternative to the 85mm for those more intimate ceremonies. It's also a wonderfully light and sharp piece of glass, I'd highly recommend it.
If you've went down the 24-200 route then I still recommend adding an 85mm. It will give you the kind of buttery background you can get with your 70-200 at 200mm but without you needing to be miles away from your couple. Shooting weddings is all about making a connection with the people you're photographing and it's tough to do that from a different postcode! Crucially the 85mm doesn't have to be expensive.
So what is the ideal lens for wedding photography? There isn't one. The best thing anyone can do is work out what style of shooting they like to do, look at their budget and take it from there.