It's impossible to say without knowing what your game is. If you don't have a game, I would strongly suggest you first focus on getting a game out and getting funding. Once you have, say, $100/month of funding or a relative equivalent by some other measure, THEN discuss who gets how much. You have no idea how successful your game will be, and you should be focused on the game, with money being a side-effect.The
The workload can be balanced differently, leaning more on one person than another depending entirely on what kind of game you're making.
Let's take into account a few games: Corruption of Champions, Overwhored, and Snow Daze.
Corruption of Champions:
This uses a custom engine written in Actionscript (Flash). This game focuses on transformations, and the main output is text. There are some character portraits, but that's it for the artist. The programmer has the hardest job here, given how CoC's event system is wired, how the game focuses hard on transformations, and CoC's general design. The writer has a tough job too, in that they need to account for different player transformations. One example: You can't write, in a scene, that a non-player character reaches between the player's legs, because the player may have a naga tail.
Overwhored:
This uses RPGMaker, so there's not a heavy need for a programmer. The programmer's job here is more in making the battle system work. Someone has to figure out the leveling system, how to balance out combat, what levels trigger what abilities, and to plug characters in. Items also need to be written. But the programmer's job is made much easier in that RPGMaker is made for this kind of game, so it has an existing framework and community to lean on. Just, you know, don't let 'em know you're making a sex game in case that ruffles feathers.
What I really like about Overwhored is the dialogue. The conversations are witty. The npcs don't feel like stock 'fuck it, whatever' kind of people. They're part of this fucked up world. The art is also in a consistent style (all/most done by sleepymaid, I think) and very good. Here the writer and the artist are going to be where the bulk of the work is at. The adult content consists of a static picture, plus text content.
Snow Daze:
The programming for this is very easy. It's branching choices and pretty easy to do. The writing is very good in this, but since there are no mechanics to speak of, the art and voice acting really sell it. The adult content is in having, say, one of the girls bark for you while naked and getting a picture of it (as well as the audio).
All of these games are very good, and yet they focus on different areas. What contributions are made, and what areas the game depends on most should be the driver behind helping decide who gets what.