It depends on what you want out of a roleplay. Free is fast and uncomplicated, but the way people write makes my eyes bleed, and I work full time so I can't keep up with the speedposting anyway. Casual is the middle ground, but that essentially means the worst of both worlds for me. 

Advanced means big, meaningful posts from each of the contributors about once or twice per week, which fits the distribution of free time that employed adults or college students usually have.