The specs are too close to tell you anything meaningful. Speakers with very close specs can still sound very different from one another. While you can make a short list by using specs to weed out non-contenders these specs are close enough that you need to actually hear them to determine your preference.
What amp do you have? 15 watts is a lot of power from 300B amps unless it uses more than one tube per channel. Are you sure it is 15 watts?
If your budget is up to $6K I would get some horns like Avantgardes or good lowther based speakers like the Beauhorns. You want to be in the +100dB range for efficiency to work with 15 watts, not 90dB.
What amp do you have? 15 watts is a lot of power from 300B amps unless it uses more than one tube per channel. Are you sure it is 15 watts?
If your budget is up to $6K I would get some horns like Avantgardes or good lowther based speakers like the Beauhorns. You want to be in the +100dB range for efficiency to work with 15 watts, not 90dB.