I'm working on a design for an RPG game, and I'm having some doubts about the skill and level system. I'm going for a more casual, explorative gaming experience and so thought about lowering the game complexity by simplifying character progression. But I'm having trouble deciding between the following:

• Progression through leveling, no complex skill progression, leveling increases base stats.
• Progression through skills, no leveling or base stat changes, skills progress through usage.
• Progression through items, more focus on stat-changing items, items confer skills, no leveling.

However, I'm uncertain what the effects on gameplay might be in the end. So, my question is this:

What would be the effects of choosing one of the above alternatives over the others? (Particularly with regards to the style and feel of the gameplay)

My take on it is that the first sacrifices more frequent rewards and customization in favor of a simpler gameplay; the second sacrifices explicit customization and player control in favor of more frequent rewards and a somewhat simpler gameplay; while the third sacrifices inventory simplicity and a player metric in favor of player control, customization and progression simplicity.

Addendum: I'm not really limiting myself to the above three, they are just the ones I liked most and am primarily interested in.