all the way to the end of the countertop.

How did you deal with the other areas with no stopping point? You don't show any photos of the rest of the backsplash area. Anyway, it should be the same treatment.

No other corners so it’s irrelevant

I would do back only.

All the way out and 3 inches or so above the lower cab edge.

I wouldn’t want a semi permanent finish for a small appliance that might not stay there, keep getting used etc - if it were me I’d keep the tile against the back wall only and if I needed protection for the wall I’d slip a cutting board in there (FWIW in a previous house we had an upper cab go yellow from a regular toaster)

Another vote for tiling only the back.

Ours is installed like my brown cutout rendering above and it's great. Or nothing there like @la_laGirl and @Sara . But NOT part way out as in your proposed photos.

Just the back is tiled in my kitchen. It never occurred to me to tile the side wall.

Side tiled, with the top edge ending at the bottom of the cabinets, and the outer edge goes all the way to the edge of counter. The side should be tiled for protection as you said. And it should be taken to the edge of the counter both to protect that entire area, and to have it look finished, rather than half-finished. I do not understand the purpose of taking it 3" above the bottom of the cabinets that is shown above; I prefer the tile and bottom of the cabinets to all be in a line.

My kitchen was done in 2019. I make at least one pot of coffee a day for the last 4 years and the painted wall has never gotten dirty. You are the only one who knows how you use your kitchen. I think it’s a personal preference. Good luck with whatever you decide.

Agree it’s just preference. Mine would be back only.

Another vote for back only unless you know from experience you will get that side dirty

Thank you all - decision made . Back wall only