I use Linux mainly because of its ease of use in terms of development. I would be interested in hearing your arguments for the Mac. My friend recently got a Mac, and unbeknown to himself was forced to download a 2.something GB download for the developer pack just so he could get GCC, Now I know there are better ways to achieve this, but this to me seems counter productive.
I used linux on a Thinkpad T41 for years.
The problems are not so much the real development stuff, more about the things that you have to do apart from that, like cinerama mode for an external screen (took me several attempts with the configuration file), make beamers work, wireless (cough), permanent fan noise you want to get rid of but the power management did not work, kde that tries to copy windows ("you have old files on your destop", "miranda apeared in skype" while you try to give a presentation ) and thus is not usable IMHO (I used window maker which is fine), no decent office suite (open office is a copy of MS office but 10 years behind), software you just want to try, but have to compile, shared libraries problems, no bootable backup, no first class image manipulating software (gimp just sucks compared to photoshop), ... Is that sufficient?
Well, of course, this is all fixed in the latest version ;O) and everything has been solved by someone - get the point?
Linux is a very stable and reliable system though, once you have installed an configured it properly. But Mac OS is that too, and configuring it is quick and easy.
I am much more concerned about Apples latest iCloud stuff and about privacy on Macs. Thought already about using linux again. But productivity is certainly much higher on Macs.
Development on Macs is certainly not without problems. I think Apples philosophy is to provide the whole package to assure there is not problem because of missing parts.
Being a Mac developer is also not free anymore. XCode 4 is the first version of the development tools that costs money. Nothing compared to Visual Studio of course, but the direction is not so great.
I usually ignore all these tools and use Netbeans or bbedit and commandline tools. I can afford that because I build scientific software in java and don't have to deal with Apples packages.
After that, both Linux and Mac are Unix systems and have package managers that can install stuff (third party on Mac). Personally, I spend most of my time in Chrome, a terminal and Vim. On OSX. Because I like it that way. But I could certainly replicate that same development process in some Linux distro.
Also, many Linux applications work just fine on OSX but not the other way around. So there is some argument for choosing OSX. Also, all that basic stuff like connecting to networks, having MS Office, etc. just plain works better on OSX. But to each his own.
I stay with Linux as my laptop is fully supported (i.e all devices work seamlessly across almost every distribution I've tried) and I generally find it faster and I guess I also like the lack of a price tag I as a student experience with Linux.
I would rather put on whatever I want later.
A default Ubuntu install I think has Python on board. Not as sure about Ruby.
By the way, I think that this is not a problem at all. I'd prefer a clean, lean system to Windows any day.
But if you really want to do work and not always fight against your tool of choice, linux is not the thing to use.
For coding, I replaced it with Mac OS. This saves me 98% of the problems I had on linux.
To be fair: I wouldn't know an out-of-the-box way to convert a MS Access file to csv on the Mac either.