I have basic idea of how asp .Net works, but finds all framework hard to use if you are a newbie. I found compiling, web applications vs websites and all that stuff you should know to program in asp .net a bit tedious and so personally I go with php to create small, to medium applications for my clients. There are couple of reasons for it:

1. php is easy scripting language, top to bottom and you done. You still can create objects, classes and if you have idea of MVC its fairly easy to create basic structure yourself so you can keep you presentation layer "relatively" clean. Although I find myself still mixing basic logic in my view's, I am trying to stick to booleans, and for each loops. ASP .net keeps it cleaner as far as I know and I agree that this is great.

2. Heaps of free stuff for php and lots of help everywhere

3. Although choice of IDE's for php is very limited, I still don't have to be stuck with VisualStudio. Lets be honest.. you can program in whatever you like but does anyone uses anything else other than VS? For basic applications I create, Visual Studio doesn't come even close to notepad :) / phpEdit (or similar) combination. It lacks of many features I constantly use, although armies of developers are using it and it must be for good reason. Personally not a big fan of VS though. Being on the market for that long should make editing much easier.

4. I know .Net comes with awesome set of controls, validators etc. which is truly awesome. For me the problem starts if I want my validator to behave slightly different way and lets say fade in/out error messages. I know its possible to extend it behavior, plug into lifecycle and output different JS to the client and so on. I just never see it happen in places I work, and honestly, I don't even think most of .net developers I worked with during last couple of years would know how to do that. In php I have to grab some plugin for jQuery and use it for validation, which is fairly easy task once you had done it before. Again I'm sure its easy for .net gurus, but for newbie like me its almost impossible.

5. I found that many asp .net programmers are very limited in what they are able to do and basically whack together .net applications using same lame set of controls, not even bothering in looking into how it works and what if? Now I don't want to anger anyone :) I know there is huge number of excellent .Net developers who know their stuff and are able to extend controls and do all that magic in no time. I found it a bit annoying though that many of them stick to what is provided without even trying to make it better. Nothing against .net here, just a thought really :)

6. I remember when asp.net came out the idea was that front-end people will not be able to screw anything up and do their fron-end stuff without worrying what happens behind. Now its never that easy and I always tend to get server side people to fix this and that during development. Things like ID's assigned to controls can very easily make your application break and if someone is pure HTML guy using VS its easy to break something.

Thats my thoughs on php and .net and reasons why for my work I go with php. I know that once learned asp .net is awesome technology and summing all up php doesn't even come close to it. For someone like me however, individually developing small basic applications for clients, php seems to work much better. Please let me know your thoughts on the above :)