It depends a lot on what you cook really. My cooktop currently maxes out at 14K BTU on the big burners. It's not enough. I've got an outdoor stove with 3 30K BTU burners. It's most impressive. But not what I want all the time either. To go with more burner power requires home modification however to make it safe. Cabinet offsets, wall covering that's rated for the heat, hood requirements and more. It's not a trivial upgrade to more burner power.
For the cook top, in a 4 burner config, I'd like a 30K BTU burner, 2 at about 22.5K BTU spaced appropriately for a double burner griddle and 1 at 10K on down with a good low heat for simmer. The big burner would be my boiler/stirfry. The medium burners are for general saute and other work. The little one is for more specialty cooking, but still with enough oomph to steam some vegies.
As to the oven. 500 F is plenty for standard work, but the broilers are weak. Get one with an upgraded broiler, or broiler drawer perhaps. And gas for the broiler, but electric for the oven if possible.
That's my opinion.