What are the best factions to build decks for?

Wyldkard said:

The ones that suit your playstyle.

Or, the ones you most enjoy playing.

Or, the ones you will most enjoy building.

Or, the ones you haven't tried yet.

Or, the ones that will beat your local metagame.

it really depends on your play style and personality. For example, I am a greedy SOB so I play Weyland and gain lots of $$$