Hello, are you planning to keep the 4" granite? If yes, the glass tile size is better, but I'm not sure either color is best; what is your granite?

Yes, keeping the 4 inch tile, granite is what you see, black pearl.

Thanks so much! I agreed, never thought of that! Hopefully pops right off..

How to fill in the 4 inch space after removing the backsplash under the sink with 3 inch tile ? Leaning toward the bevelled subway tiles in white which is 3 inches. What do yo think? Maybe find a 4 inch tile..

The installer will cut tiles, to keep the pattern going, no need to pick tile by the size that fits under window.