Any kind of high kelvin color bulb will look nice, like over 10,000 kelvin. For reference, 5000 kelvin is about noontime sun in the tropics, and is pretty yellowish. Pure white is about 6700 kelvin, and past that gets more purple/bluish.
I think planted tanks look good with 6700 bulbs, and african/rock only tanks look nice with those 15-18000 bulbs. The downside of high kelvin bulbs is they don't appear as visually bright as lower kelvin bulbs, so you may need more wattage to compensate.