ME is an interesting one. I don't really think FO3 encapsulated the 'RP' elements terribly well (But it was a pretty awesome game outside of that) though it was a fairly good step up from Oblivion. ME, I'm pretty sure, can be classed as a fairly good approximation of what an RPG should be.

Primarily I base this opinion on the fact that, well, you've got choices and those choices can have consequences. The most striking example is Wrex when you're on Virmire, where your character build choices throughout the game can influence your available dialogue options and thus, the outcome of the scenario. Which is pretty much the entire point of the genre. (See also: The original Fallout, where proper dialogue choices, informed by the right stats and having done the right preceding quests, mean you can basically talk the last boss out of it.) Unfortunately it looks like the real promise of the series - that your choices would persist through the entire trilogy - might not be lived up to. Even so it's nice that sarsaparilla matters.

Actually on further thinking I might be being unkind to FO3. It does have choices and consequences (Derp, Megaton). I just feel they're poorly implemented and quite bluntly applied.