Co-Founders: Should I look for Ruby/Rails or Python/Django developer, although I already know a good PHP developer?

Cofounders' disagree all the time. It's very common for founders to leave over disagreement, but it's great that you still want to pursue this venture. I have used angellist before so quite aware of it's feature set. If your web application is similar to angelList don't worry at all PHP would do just fine. It's just right for the job. Programmers have their own taste and are baised towards their tools. Would like to suggest that a) You get the wireframes of the site in place so that the idea is solidified, b) Draft a short requirement document and put it out on sites like elance, odesk etc. I think you should be able to outsource the coding work for quite cheap, c) Believe it or not I have a MBA graduate friend who got so frustated with finding a cofounder that he self taugh himself HTML/CSS used the bootstrap framework and created the User Interface. Later he went on to learn Python and create the first version. Which was very crappy to say the least and the web application never took off but what the hell he did it. I recall what the founder of the first startup I was employed once told me "You got to do with what you have and you better do it fast for you don't know for how long you have it" God Speed.

If you've got a PHP developer, stick with PHP, for pete's sake. The amount of productivity that you *might* gain by moving to a different language will not be exceeded by the transition cost or the fact that it's harder to hire help with Ruby/Rails.

A good PHP developer proficient in a framework such as CakePHP, Yii or Zend will do equally good as a good Rails/Django developer. PHP is a language and Rails/Django are frameworks on top of Ruby/Python. If you have to compare them, a better approach would be to compare Zend/CakePHP to Rails and Django. They all come packed with almost a similar set of features. Rails as a Framework is Epic and enforces very strict standards to ensure your application does everything the right way. A set of features on AngelList can be replicated easily in PHP. [Facebook still uses PHP for its Content Delivery Layer]. Although choose a Front-end developer wisely as the application you are planning will require a great UI/UX. All the best!

First you need to decide the requirement of your application. Selecting a language highly depends on type of application you are building. Python, Ruby are just other languages like PHP. Don't forget that big applications like Facebook are also primarily coded in PHP Edited - I am currently working on a social app where users collaborate with each other and am using php with codeigniter framework..also I personally know few more apps written in Php. Now your requirement can be fulfilled by both PHP as well as Ruby..but if you are comfortable with your programmer friend and both have same vision, then why lose him and go in search for other. In startups, people are more important..as Steve jobs rightly said -"Success of a startup is decided by first 10 employees" Today Facebook/Google are more in talks for their work culture as compared to their technology.. And your Co-founders and employees make the culture :) They make a product successful. Technology just helps them to do so :)

As long as you and your co-founder have good chemistry and are on the same page as to where the application might/should go, I don't think the stack matters at all. If your idea is truly amazing and your co-founder's execution is amazing - tech stack is not even a problem. Find a good programmer - doesn't matter what language or framework he knows. A good programmer can easily pick up any other language or framework easily.

Sounds to me like your "business" is putting the cart before the horse, not the way it should be, and I'm wondering if this is a business venture or an "idea." Where is the profit coming from? What's the marketability? What difference does it make if you have a developer who is a master of Ruby or a good PHP developer? First of all, they're not the same thing and you didn't explain why you simply can't use WordPress or any other CMS or platform for your idea. You're not making the app, the developer is, so whatever is used is really irrelevant; with profit, marketing, partnering being moreso. I would take a step back and complete a business plan or two for online ventures before spending another minute or another dollar on this venture personally, and re-examine goals. WordPress is the most popular CMS on the planet, and can build almost anything; so why not work with a developer who can work with commonly used tools, and why not develop a business plan around this first?

Many different frameworks available for PHP. Laravel is a strong up and comer. A product is more than it's code. Nail down what you are developing first. Then go and develop it after you do some idea validity checking.