Alea
"I won! I won!"
The thrill of gambling and winning, straight out. Alea requires randomness which can be won or lost in the perception of the player. Alea is common almost across the board; it's one of the reasons that diceless games often don't do that well.
Catharsis
"That was... intense."
There’s a feeling of release that follows an intense or overwhelming experience. This may (or may not) be tied to character-identification by the player. Catharsis does not necessarily require a tragic or traumatic experience, but doe require emotional content and investment. And, yes, there’s argument about whether catharsis (especially the strong-form versions, which *do* hit on the tragic or traumatic buttons) is a good idea in RPGs. That's an argument for a whole other day, if ever.
Closure
"And that's how it happened."
The feeling that there is nothing more that need be done, and that the thing is finished, is something many people enjoy out of games. Contentment requires closure and resolution to whatever the matter at hand may be. This does require that either in-character goals and end points be clear, or that everyone is actively listening and aware of the desire.
Emergence
"Hey, these go together!
The thrill of having a singular thing come together from apparently disparate pieces. In RPGs, this usually means that the fictional events of play come together into some roughly story- or plot-like fashion.
Expression
"My creativity matters!"
This one is tricky, because it covers a lot of ground. Some people want to create bits of world that surround a character, or create the world itself, or write fiction based on the game, or you-name-it. Each kind of creative impulse comes with different preferences on using the modes of play.
Fiero
"I have overcome!"
The feeling of winning, of defeating a challenge, or overcoming adversity. Fiero is lifted from serious game-study, and included here because I think it sounds awesome. Fiero. Go on, say it out loud. Anyhow, people looking for that feeling are on the lookout for adversity – and they tend to want adversity where they can be partisan for their characters and the GM is actually playing against them a bit. Fiero doesn't come easily if the challenge isn't challenging.
Humour
"*Gigglegiggle*thud*"
Games can be played for laughs, and often are. Amusement is served by all four of the modes. Notably, a player that really pushes for it will often end up pushing for collaboration, even to the point of attempting to dictate the actions of other player characters, because some of the humor that comes to mind most easily can step outside the specific boundaries of authority the other modes often lay down.
Kairosis
"Llew gets back up again. And he knows who he is, now."
This is the enjoyment of seeing (or experiencing, vicariously), the fullfillment or change that is natural to a character as pressure is exerted on them. Much of the time, this is about the character becoming who they 'ought' to be.
Kenosis
"I'm in the groove."
Some players seek the feeling of being deeply engaged in their character or in the fiction as a whole. Players looking for this (especially really serious kinds) often aim for a lot of characterisation. They also often (but not always) want to avoid types of action that will pull them “out of the groove”. Flow states are related to this; some are about getting deep into character, some are about other things.
Ludus
"I am the master of the rules!"
Some people also take their fun a little more seriously. The rules-tinkerers and the optimal-builders are chasing the fun that often sits on the opposite end of the spectrum from the people looking for paidial fun. To someone looking for ludus fun, the rules are the game, a toy that the group is here to play with. Wherever the mechanics of the game are, whatever modes they attach to, that’s where ludus-seekers go.
Naches
"You've come a long way, John."
This is a social pleasure - a parent seeing their child doing well feels naches. Taking pride in the accomplishements of others, sometimes in the form of "I taught them that!" is naches. Teaching people to play a game and seeing them love it is naches.
Participation
"I'm part of this!"
For most gamers, the game and the acts that make up “playing the game” are a way of being social. People looking to get especially significant gameplay-as-socialisation often try to match their other goals with the rest of the group. Participation is socialisation chanelled into play.
Paidia
"What would be awesome, right now?"
Paidia is free-wheeling player fun, where rules are a convenience. Players looking to get some Paidial fun would prefer winging the rules-calls, going for whatever feels right at the moment. Novelty and wonder are often, but not always, associated with this goal. Off-the-cuff characters are sometimes signals that someone wants this kind of fun.
Sensory Enjoyment
"There's something satisfying about a big handful of dice."
Miniatures, maps, game book illustration, tokens, and dice are all visual and tactile things that are enjoyable about RPGs. I haven’t yet met anyone that considers these things their number one priority, but they show up on a lot of lists.
Facsimile
"That's exactly it!"
Successful portrayal of a pursued idiom. E.g., a player saying a particularly Star Wars-appropriate thing in a Star Wars game ("I discovered the illusion by looking to the Force; the senses can be deceived."), or a group resolving a mission in said game in a particularly Star Wars-appropriate fashion (Good beats evil, the protagonists grow, not quite happily-ever-after but close enough to end on).
Protection
"This will not be broken!"
Defending a game's logic, function, continuity, or aesthetic from threatened violation. Example: "If trolls in this game are incinerated by sunlight, how did the troll statue get from A to B without any tracks heading off for shade?" GM looks uncomfortable, obviously having erred. "Maybe traveling trolls carry a shade tent with them so they can march during daytime." GM brightens at this player suggestion, and says, "You did notice some tiny lines in the dirt, which could be the dragging of tent stakes..."
Emotional Displacement
Actually feeling what your character feels in their current situation. I think there's some appeal to doing this regardless of exactly which emotion the character is experiencing, but I could be wrong.
Sensory Displacement
Achieving a degree of vivid imagination of the setting, in which you can almost see/hear/smell/taste/feel the setting. Again, I suspect there's an appeal to doing this regardless of what the setting holds, but maybe not.
Schadenfreude
"Ha ha!" (as in Nelson from the Simpsons)
Enjoying the misery of others. I don't see how enjoying deep and sincere misery could be acceptable in RPGs, but a little bit of chortling at someone else's tragic die roll or some such seems to play just fine.