Not the OP, but I can shed some of my thoughts as I've been at WeWork, local co-working spaces, and leased our own office space.
Most co-working spaces are cheaper, but they won't offer as many amenities as WeWork. 24-hour building access, conference rooms (for clients and internal meetings), phone booths, free coffee, a kitchen to utilize for lunch, highspeed internet (1,000Mbps if you use the ethernet jack) and roughly around 200Mbps on their free Wifi, free printing up to a certain volume every month. Did I forget the best perk? With your WeWork membership you can actually access any other WeWork location in the world and work out of there.
There were a number of times when I was traveling, I would just book a desk at another city or country for a single conference room credit.
Just a few positives off the top of my head compared to other coworking spaces. While you can find some with the same benefits, WeWork also wins with their decor and natural lighting in some offices. They also make it easy for startups to expand if they need more desk space. You rent on a monthly basis, whereas most places do yearly contracts.
Now let's talk about leasing your own space and all the headache that goes with it. At least in NYC, most places don't have a kitchen. So if you want a place to make coffee and wash your hands that's not the bathroom, you'll need to pay someone to have it installed.
You'll also need to set up the internet and electricity. And since you're on a lease, there's a good chance the landlord will raise the prices sky high the moment the contract is up. You'll actually end up paying relatively close to WeWork's price per month with a lot more things to manage on your own.
Think of it as self-hosting versus managed hosting. Small scale startups don't want to deal with all the headache so they just opt for WeWork. It's a reputable brand and they know what they are getting at any WeWork. It's similar to walking into a Hilton or Marriot. You know what to expect from it.
Hope that helps!