Not many of the company is going for SQL 2014, some of us might still go for SQL 2008 R2, which I strong suggest to go for SQL 2012 minimum, but sometimes the vendor application doesn't support the newer version of SQL, then there don't have much choice for us. Even so, please do not use Windows 2008 R2 standard, at least use Windows server 2012 standard. You might think, if we put everything on Enterprise edition will be fine, well, yes, but sometimes when you are low on budget, that might be your best bet.

The reason for that is, if you look more closely, SQL 2008 R2 standard can support up to 64Gb of memory, but Windows server 2008 R2 standard only can go up to 32Gb, so you cannot put more memory for SQL if it does need it or more instances on the same machine. Looking at Windows server 2012 standard, it support 4Tb, which will put you in a much better position not just for SQL 2008 R2 standard, but also allow you to plan more instances on it if required. 

So please do use Windows server 2012 Standard even if you are running SQL 2008 R2, since you will be getting the windows 2012 license anyway, giving yourself more room to plan or just the extra 32Gb for your standard version of SQL is always nice.