Dominion expansions in order of release date...
Intrigue: (25 new action cards) Leads to cutthroat actions and negotiations. Really varies the effects of abilities of cards during action phase. New ways to get VP. If you want to laugh, grimace, and actually interact with your friends, then this is the expansion. It's Game of Thrones in a box.
Seaside: (25) Slows down the game due to persisting effects.... you must concentrate on game, so less chatting... but it has some really powerful cards. There are also coin and embargo tokens... you start managing stats.
Alchemy: (12) Introduces new potion currency. Can take longer to build effective deck. I don't like it at all, even though it has lots of plus action cards. If you play from multiple expansions, then Alchemy gets really watered down. I think it should only be played by itself or with the base game.
Prosperity: (25) Money, money, money. Congratulations, you're a Lannister. Higher denomination currency and VP. Winning player might have quadruple the VPs of base game. A fast and fortunate player may find him/herself gaining a huge economic lead... but this can be offset by Thief and other attack/trash actions.
Cornucopia: (13) I've never played it.
Hinterlands: (26) Buy phase (gain card) abilities are increased.
Dark Ages: (the internet says 35, but I think there might be more, I dont' remember) Lots of attacks and trash triggered abilities. It's complete anarchy.
Guilds: (13) I've not played it.
Fried Egg, I would strongly recommend Intrigue as your first expansion. Prosperity and Seaside introduce powerful cards and change the basic rules. They're fun, but they don't sound like what you want. Alchemy is a different animal altogether... In over a hundred games, I've only ever seen one person win by using Alchemy cards instead of Base or other expansion cards. Intrigue introduces enough trickery to be fun, but probably Dark Ages is... well, the Dark Ages... it can devolve into utter chaos.
So my friends and I draw from more than 170 action cards when we play. I cannot remember them all. I don't know what all of them do. Some have gain abilities, some attack, some defend, some trash cards, some steal, some give cards, some have abilities that endure for a turn, some give VP... What I'm saying is, you need to play with people you like and trust. Due to the speed of play, chatting, and reshuffling decks, it would be very easy for an unscrupulous player to cheat. And a person who cheats his friends over a parlor game is a total loser. With that being said, mistakes are inevitably made...
"Last turn, I forgot to get my copper from my Madman... Can I do it now?"
"After Thief, I'll play my Village... +2 actions... Wait! I needed to play my Village and then my Thief... Can I back up?"
"How can you still have five cards? I played Militia, you idiot!"
"Stop! Why are you drawing? It's not your turn... oh, I played Council Room... I forgot. Okay, everyone gets to draw a card. Doh!"
"You cannot Remodel a Silver into a Gold because the cost is three more. You played Remodel, it allows you to trade in for a cost of only two."