Honestly, I'm fine with getting the default companions over time, but I want to be able to start with a full custom party from the beginning.

In few words it would be Icewind Dale or Baldur's Gate? I would choose a mix of both:

1) giving the opportunity to create a full party as Icewind Dale does or without the multiplayer stuff from Baldur's Gate II (you can create the whole party by choosing multiplayer and controlling everyone), but you can still "recruit" people around the world or...

2) starting as a lone wolf and picking up party members as you go on the story or exploring.

 

Choices are always welcome, there is no need to exclude anything. "I want to adventure alone and meet people willing to join me" excellent. "I want to customize every member of my party, I don´t want to share my wealth with anybody else", don´t worry, you can do it.

Let it start off like snowball rolling down a mountain; very small at first yet expanding steadily with the plot.

This poll is kind of irrelevant because of the Adventurer's Guild concept, which would allow players to hire generic companions without complex writing, dialogue or story involvement

 

I never liked the idea of Adventurer's Guild it's like filling in the game. I think in cRPGs every character must weight on his place, with Adventurer's Guild it becomes more like RTS game.

I allways liked to play with 3-4 characters instead of 6, it gives me different approach through the game

I like when there are one or two "secret" characters that are very difficult to get, because they are potential adversaries or martyrs that require great charisma or skill to recruit.