I got the Dell Professional 13 sleeve based on another member's recommendation and really like it:

It's very nice - perfect fit, I like a sleeve with handles and the option of a shoulder strap, and a zipper pocket for accessories. It's nice quality, textured zipped pulls, hidden zipper, good padding. It's got an MSRP of $30, you can get it for $10 now on amazon

https://www.amazon.com/gp/product/B01N5FZHAQ/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1