I vote for C#/MSSQL, but that is because I am part of the borg (hey, it pays my bills!). I feel MySQL is a toy database as the most popular installed version (4.0.22 I think) is utter crap*. No subselects and lack of stored procedures/functions make things way harder than need to be. They are easier and faster since the sql engine doesn't need to verify things like syntax.. it's already been compiled!
No matter what you go with, make sure it is a object oriented language.
*I messed with beta 5.x versions of MySQL and while it has stored procedures and functions, there were still many things broken and flat out missing that any other decent database has. Things might have been fixed by then. And I like Microsoft. Flame away.
//Edit: Tired and I typed some crap that didn't make sense
