Without seeing the rest of the room ( curtains , dining or bar stool colours , etc ) I'd go for a primary colour -- blue or red or orange or yellow .

Actually , thats not quite true -- personally , I'd go for subway tiles in the above primary colours ( or black ) , or those tiles that are 25mm x 200mm in charcoal , grey , and metallic colours . Those would need grouting though , but they'd be my first choice -- a colourful glass splashback would be my 2nd choice .

I think using the same as benchtop would look great if you aren't keen on tiles.

I agree glass may not suit the style. I do think a warm grey tile with a bit of texture would look great (look how nice the grey/charcoal platter looks!!) but i understand your dislike of grout!

On the other hand if you had a dark grout to match the tile you wouldn't have to worry about the cleaning so much:)

Undoubtedly the glasses are trending in these days, Moreover, You can see the wonderful match able collection from the source of great Splashbacks Glass.