The 6SN7 would be a good choice, assuming they can bring something worthy to the market. It would appear then, that they are not necessarily looking to make tubes that are a reissue of what Western Electric made in the past.
If they were going to reissue what they have made, the 350B would be a nice choice (a replacement for 6L6 or KT66). The 274B rectifier would be a nice reissue item too.
What I would hope for most in anything that they put out that they at least try to emulate past Western Electric practice of making very durable and reliable tubes.