- Which faction is stronger? (Necropolis, Tower, or Conflux)

Conflux is good in many ways, except for one: weak units.

And we should also add: they are very expensive.

Although, I never really understood why it's difficult to start with a Tower. I would say the opposite, especially with Master Gremlins; if you manage to get at least 100 of them, it will be very convenient. Of course, I'm not considering the cheater Solmyr. :)
With him, I don't think there's such a problem at all.