Frameworks and languages are a lot like databases. They all achieve the same thing, they're just all slightly different and good for different purposes. I sometimes use MySQL, other times I'll use PostgreSQL, sometimes I might use a graph database like Neo4j or other times I might even use something like MongoDB.

The Rails community has been around a lot longer than Laravel's community, so you can't even compare them. The only community worthy of being compared to Rails is Codeigniter's and at the peak of Codeigniter's popularity, I would argue Codeigniter had the bigger community. Laravel is a mere couple of years old, the community is already pretty strong. Lets reevaluate soon when the right amount of time has passed and then see where the community is at. You only have to look at the amount of Github stars to see how popular it is.

PHP is ubiquitous on shared hosting platforms, there aren't that many "shared" Rails hosters out there. Morts still use shared hosters.

It would be in the best interests of Laravel for Symfony to succeed, but you have to realise they're targeting two different subsets of users. I think what makes Laravel more appealing to me as a developer is it takes the good from the likes of Symfony, takes the great documentation and accessibility aspect from Codeigniter all while remaining a relatively soft opinionated framework, it provides you with a structure but the IoC container means you can structure it however you want. The Blade templating system is fantastic, the ORM is feature-rich and very powerful and the addition of database migrations right out of the box.

There isn't a lot of different between Laravel and Symfony considering they share similar components and the unique selling points of Laravel are components that can be used within a Symfony 2 application. I think Laravel gives you a little more out-of-the-box, whereas Symfony makes you add what you need and I can see the benefits from both sides of the fence. If you want to compare frameworks, a real comparison would be Laravel and Silex.

One aspect I like about Symfony is the ability to define routes 4 different ways; YAML, PHP, XML and Annotations in a controller. Compared to Laravel's routes.php file. If you're a developer that wants to customise absolutely every single aspect Symfony is probably a better choice, if you're happy with the guiding hand Laravel gives you out-of-the-box and don't care what format your configuration files and routes are written in (amongst other aspects), Laravel is the better choice. The learning curve of Symfony is far higher than Laravel due to the amount of configuration it allows you to do and the fact it is completely unopinionated.

So, while Taylor didn't build every aspect of the framework (a very well-known fact), there are certain aspects he did build specifically for Laravel. He also took the time to piece all of the components together from Symfony and other authors to create what is arguably one of the most developer friendly PHP frameworks since Codeigniter hit the scene in 2007. Before Laravel came along, I can't recall anyone else attempting to make a consumer friendly framework, can you?

The best example has to be the templating languages used. Blade is a weird port of ASP.NET MVC's Razor syntax and I've never understood why anyone would use it over Twig (or even just raw PHP).