I guess I'm a little bit of all three. For the most part, I'm a narrative and ruleset focused player, and I tend to most enjoy games that focus on those things. However, when I play an Elder Scrolls game, I get into the simulation aspect, having my character sleep at night and eat food at meal times, even if it's not required by the game. Simulation is really the only way a game like Skyrim can be enjoyed from an RP perspective, because the other two elements are pretty threadbare.
However, when I play most games, simulation is not something I even think about. Only Bethesda games seem to bring that out in me.
I think most (if not all) RPGers are a little bit of all three. It's more a matter of how different players prioritize these elements.
Thinking more about it, I think each of these elements has to be further specified for a game to count as an RPG. For example, the simulation aspect has to not only represent the sensory elements of the world, but also the logical or manipulable elements: things not only have to look like real objects, but they have to provide the player with a broad number of ways to interact with the environment. An action game typically tries to simulate visual and physical properties, but doesn't typically try to extend the number of usable elements beyond what is strictly necessary. Typically, you have guns and health kits and maybe vehicles. RPGs typically include numerous redundant elements (elements that add to the game without being required to complete it): eg. harvestable plants and crafting materials, work stations (alchemy, smithing, enchanting, cooking), food and drink, chairs, beds, containers to store things in, books to read, 'junk' objects that can be picked up, stored in inventory, sold, etc. A game with a large number of interactive elements and poor graphics can provide a better simulation than a game with good graphics and a restricted set of items.
Every game is bound by rules, but RPG rulesets must specifically implement a means of player progression: a mechanic for improving a character's stats over time that supports alternate builds. They also typically provide the player with some way to choose from different character presets or allow the player to create a custom character. Different character builds should have different strengths and weaknesses. Ideally, they will also provide the player with party mechanics that allow the player to control one or more NPCs (or allow the player to join other players over a network).
Narrative, in turn, isn't generally a straightforward linear affair as it typically is in other games but allows the player to choose different responses leading to different results. There has to be some branching in the middle, even if the end is ultimately the same.
If we use these provisions we can say that a (generic) action game isn't an RPG even though it includes simulation, rules, and narrative because the simulation does not extend redundantly into the fictional world, the rules do not permit the formation of different character builds based on player choice, and the narrative is linear. Is it too big a stretch to say that a game that provides more types of interaction with the environment, more choices of character build, and more branches in the narrative is (all other things being equal) a better RPG than one that does each of these things less well?
That would make Skyrim a middling sort of RPG. The simulation is fairly good, the mechanics are fairly uneven (some good, some bad), and the narrative is pretty thin. People who hate the game the most are probably the people who value narrative over the other two, or people who value rules and narrative above simulation. People who value simulation highly are going to be the most satisfied overall.
What are your thoughts?