Be a Lawman, or a rancher, or a Native American, or a rustler, or a gambler, or a bounty hunter, or a preacher, or a bank robber, or a farmer, or a stagecoach driver, or a saloon keeper...
More customisation.
Keep the straighter tone of RDR, rather than the madcap GTA vibe.
Different houses, hideouts.
More of everything please!