In my opinion, it doesn't really matter ( or it shouldn't matter ). Each technology has it's advantages and disadvantages. It is true that certain server-side technologies have better support for "other certain technologies" but I don't think that the technology you end up choosing should come down only to this "feature" ( and then, we should also talk about CF - ColdFusion - because since it's and Adobe technology, one would expect that it has some additional support for other Adobe technologies, like Flex - which is kinda true ).
We could go even deeper and start comparing these technologies "hosting wise" ( not all project have a huge buget so hosting price might count in certain situations - PHP hosting is much cheaper then .NET hosting or CF ). To conclude: I think that certain projects, require certain technologies in order to be solved more easily, and most importantly: "to be solved the best way possible" ( hence certain technologies have better support for "other certain technologies" ), except if the client specifies that "I want to use X technology, I don't care what others can offer". As a developer, you shouldn't get stuck with a single technology just because you feel more comfortable with it, you should look at/analyze the application as a whole and decide which technology would suit your current problem/project the best way possible ( maybe it's PHP, maybe .NET, maybe Java... it depends on the problem you want to solve ).
As for "personal projects": ideally, you'd still choose the technology that would suit your problem the best way possible ( but I think that this is not to case in 90% of the situations ) but since you are also "the client", you can simply just choose the technology "closer to your heart" ( the one you feel more comfortable with and have more experience with ). In the end, each server-side technology should be able to solve the problem you are facing ( just that some offer a more easy, straight forward solution, and other require more time, effort and maybe even more experience ).
So, as a professional, you should strive to use the technologies that suit your current problem the best way ( no matter what that technology might involve, especially if a financial issue does not exist and the client wants the same thing that you should want: "The best possible and efficient solutions to get the most out of the final application." ) and not the ones you feel comfortable with.
Just my 2 cents.
PS: Just to avoid possible confusion: "The easy way, is not always the best way."