I've been developing web applications for about 17 1/2 years. I've worked on a huge range of what would now be called "stacks"; everything from ASP/SqlServer to Java/Oracle to Perl/MySQL and a whole bunch in between. I even worked on "web services" in 1999 using Oracle/Corba/C++ and CSV-over-HTTP.
The main thing I've learnt is that these choices made almost no difference to the success of the project. Skilled engineers using whatever tools they are experienced with make successful products.
Honestly this sums up what I have been trying to articulate for a while now. I find people put too much stock in "what x uses" or "what is x written in?"
That doesn't mean it's impossible to make bad decisions about what you use of course.
The main thing I've learnt is that these choices made almost no difference to the success of the project. Skilled engineers using whatever tools they are experienced with make successful products.