Which font are you - ABAP developers using in code editor (either in SAP GUI SE38/SE80/SE24... or in Eclipse IDE)?
I have done little research in other programming languages and I found that one of the most preffered non-default one is called Consolas.
So I gave it a try and now I can say that it is great
It is one of the pre-installed fonts in MS Windows since Vista I think...
Here is comparison between default SAP GUI font: