Deep in my heart I wish to say that the choice of your distribution is a complete non-issue. The tools you need should be available as regular packages of your distribution today. If not all, then most of them. And the community should embrace you when you come with your desire for an additional tool to be packaged or when you already come with those packages that you wish to bring back to the (re)distribution for the benefit of all. I tend to think that most if not all community-run distributions now work like that and Bioinformatics packages seem omnipresent for basic analyses in all distros. So just make your pick.
My personal choice was Debian since the community started the distribution all and still controls it. And for anyone submitting a package to Debian, one is happy for every user in one of the many "derivative distros", like Ubuntu or Mint ... or BioLinux. And after all, it is the community that I am after, not only the tools. Some good parts of us want to talk Biology, or Computational Biology for that matter, and what Debian derivative one uses is not of any concern - we can easily run everything everywhere and all bioinformatics package names are identical between the .deb distributions. The latter point is the most important to me: how quickly can others join practically with ideas, or how portable are parts of their workflows on my machine. The .deb world is big and open and collaborative.
So, with Debian we have quite an accepted server platform, BioLinux uses what Debian has and adds what it wants to add to it. Both share a repository with the DebianMed initiative (a somewhat better name IMHO may be DebianUbuntuBioLinuxMint initiative) where packaging efforts are communicated and shared between them. There are annual cross-distributional .deb sprints on Bioinformatics and then one knows each other from conferences over the years. There is no separation of DebianMed from the rest of Debian. When there is e.g. a Java package missing for a Bioinformatics package, it is added to the benefit of all Debian/Ubuntu/Mint/BioLinux users. And that transition is automated for the respective latest releases.
Particularly attractive is now an extension of BioLinux to CloudBioLinux, an Amazon Image auto-mounting relevant public datasets and with a prepared interface for Galaxy, a web-based workflow engine. Neat. There is also a Debian variant of CloudBioLinux. Also neat. Why? I am not completely sure. Most likely for two reasons: a) it is technically simple and b) there is a particular scientific and technical beauty in knowing everything on an image to be buildable, i.e. inspectable, from source code.
The enemy is not the distribution. It is time. Software changes rapidly. And while LTS (long term support) of Ubuntu is great, it becomes increasingly difficult to maintain current bioinformatics software with older Python and other everything. And when someone packages for Debian (where packaging is always performed against the very latest version) then to share that effort with other distros or the same distro's earlier releases is not always straight forward. One needs to backport. From my observation, this backporting is performed nicest by BioLinux.
When equipped with root privileges, then there is the concept of "chroot" environments that lets you install any distribution into any other. For instance, I ran Debian because of all the Bioinformatics it ships within SuSE for many years - including a second X interface that I reached with SHIFT-ALT-F8. So, have whatever you need in some production environment chrooted or just do not touch it once it is up. You can have multiple such hroots in parallel. Also learn about the dpkg tools (the package manager of .deb distros) "hold" option that avoids accidential updates of packages with the advent of a new version.
My personal suggestion is to take any Debian derivative. It does not matter which one it is. You easily change between them, e.g. my desktop I incrementally "downgraded" from Ubuntu to Debian by adding the Debian package repositories and removing the Ubuntu ones. Not that I would ultimately suggest that to everyone, rest assured that compatibility is higher than one might think. For an overview, have a look at this [?]list of "bio" packages[?] in Debian/Ubuntu.
Please do a search before reposting, besides i think the question is not what distribution would be best for bioinformatics, since it depends what are you working on, none of the distribution may have the software, packages you need. It's like asking what pencil is better for taking class notes
See related post: http://biostar.stackexchange.com/questions/9528/which-useful-debian-like-repositories-do-you-know
Agree with @raygozak. A lot of this is going to be about personal preference and the needs of the task at hand. The Linux world is huge, and so is the bioinformatics world.
I would recommend to stay with the recent and frequent updates and upgrades of Ubuntu.