I use Outlook just to keep up-to-date with what Microsoft is doing with it.
On Windows 10, I use Outlook 2013 but the font rendering in emails is shockingly blurry, just like it is on Win 8.1. Same problem in the body of Word documents.
On Windows 8.1, I reverted back to Office 2010 just to avoid the headache inducing grayscale font anti-aliasing API that Microsoft have, for reasons that defy comprehension, seen fit to inflict upon the hapless customer.
I sure hope they fix this in Office 2016. If they don't I'll have to start using Libre Office.