Mario Party - Fantastic boards, fantastic games... I spent so many childhood hours playing this game. It's a true classic... the only downside are the abundant mini-games that require you to blister the palm of your hand. The single-player mode was actually quite fun, but it's disappointing clearing it and not really unlocking anything special. Bumper Balls, Hot Rope Jump, and Running of the Bulb are flat-out iconic Mario Party games. I'm sad they haven't made a come-back. Each of the boards has a very distinct feel to it.
Mario Party 2 - I never played this as a kid, but I got it quite a few years ago. It's pretty great... it takes most of what made Mario Party 1 great and adds to it. The costumes for each map are the best feature by far... very cute. The "endings" that the winner gets is also a great addition (though I think they were in the first one to a lesser degree). Plus, they brought back Hot Rope Jump and Bumper Balls! The only reason I would rate this lower than the original is that I don't have that nostalgic feel for it, but objectively it's a better game.
Mario Party 3 - The maps were pretty fun, and it was nice adding new characters (even if I'm not particularly fond of Daisy or Waluigi). I liked that the stars from Paper Mario were the guides of the game. Duel mini-games were fun, especially Fowl Play which is one of my favorite mini-games of all time.
Mario Party 4 - Definitely the weakest of the console games for me. I honestly don't remember most of the Gamecube games too well as it's been a very long time, but MP4 is the worst. From what I do remember, it doesn't bring much new to the table. The maps were all right, but no new characters yet.
Mario Party 5 - I have a couple of friends who swear by this game, and always make us play it. It's pretty good... it was finally the first chance to play as Toad, which I greatly appreciated. The capsules were a bit annoying... but I really enjoyed the maps. Plus, Hotel Goomba is extremely fun.
Mario Party 6 - I actually looove the microphone mini-games, as cheap as they were. This one blends in with 5 and 7 for me, but I did enjoy it greatly.
Mario Party Advance - As a separate Mario game, it's pretty cute. BUT as a Mario Party game, it falls flat. And I found this game overly difficult, too, for some reason.
Mario Party 7 - I remember playing this one for the first time... I fell in love immediately. I love that Birdo was playable, AND I did manage to play an 8 player Mario Party a few times and it was an absolute blast. Very intense. I'm sad that it never really returned to the series.
Mario Party 8 - I'm not sure it utilized the Wiimote as well as it could have, but it was fun enough that I forgave it. I actually preferred the mini-games that you used the controller on the side. Definitely better than the next Wii one.
Mario Party DS - I actually LOVE the DS version of this game. The fact that they let you play with your friends if only one person has the cartridge is amazing to me. Plus, I dig the N64-esque graphics this game has. The mini-games are all extremely fun... ugh I want to play this game now.
Mario Party 9 - I was so excited for this game, but sadly... it falls flat. I *hate* the fact that you travel around in a car together. Plus, they ditch coins for the mini-stars and ditch stars completely. The maps themselves are okay, but they lack the life that the older MPs had. The one great thing from this one is the boss fights, but I think they were introduced in DS so it wasn't like it was anything new anyway.
Mario Party: Island Tour - One of the most disappointing purchases I've ever made... This game is abysmal. I appreciate that they were trying to do something different with the maps, but no. The mini-games were uninspiring, and the story mode was AWFUL, especially after getting such an adorable story mode in Mario Party DS. Blah... I've also only played this with friends once, so maybe if I play it again with friends it'll be different.