I believe GWF will be better at AOE damage and the Rogue at single target. In a party, let the GF grab aggro on the meanest mob, rogue concentrate on said mob and the GWF and CW take care of the all the adds with the cleric healing, controlling, etc as needed.
I didn't buy a Founder's pack, but do not mind paying for extra character slots as long as they are reasonabley priced. $5 for two seems reasonable to me. They need to make money somehow, and I rather pay for things like this than to be locked out of content
What might work is if some of those fun, but not game changing cantrips, like Dancing Lights, were emotes just for magic user classes. Each class could have a few exclusive emotes; i.e. twirling your sword and tossing it in the air for fighters, a brief prayer for clerics, etc.
I have no experience with this game yet, but just wanted to add in that I am finding that I need to up the brightness in a lot of new released video games lately. I'm not sure if it is due to a current trend in graphics, or I'm just getting old.