Subway tiles look good, but the grout pics up all the muck, even if you use charcoal grout - a continuous ceaser/tech-stone type splash back will blend with the short edge splash back that is already on your design and will be very practical from a cleaning perspective.
Alternatively, I have seen people use feature tiles above the oven and then put a large sheet of glass with spacers covering it.
My mistake was exactly that, a short splashback using the counter stone, and then subway tiles between the counter and the hanging cupboards, and then subway tiles also between the stove and extractor, it looked nice until 1-2 years later, the white grout turned green due to us using the green Addis dishcloth :|
This was at our previous home:
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