If it isn't broke don't fix it, unless you have a lot of time on your hands and don't mind screwing up your servers I wouldn't risk changing anything. 12.04 is supported until 2017.
That said, I've always beena bit partial to openSUSE it's quite different from Ubuntu/Debian, has a short support cycle (18 months), I've never used it on a server before but it's fun on a desktop/laptop I find it's very compatible with whatever hardware I've thrown it on even newer hardware.
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Paid supportHow to ask for help
1. Give details of your problem
2. Post any errors
3. Post relevant logs.
4. Don't hide details i.e. your domain, it just makes things harder
5. Be polite or you'll be eaten by a grue