Played for the Tarvould's Quest Mario Party League, viewable here: https://www.youtube.com/playlist?list=PLNiBuIKkhNOcetedJo2kjJwenDNYqHsFt
While not my first Mario Party, this was the main one I played as a kid, and easily the one I've sunk the most time into. I'm sad to report that it's not as good as I remembered upon revisit. It's still generally solid, with the Day/Night system allowing for some interesting experimentation within the boards. The Capsule system from 5 has been cleaned up into the Orb system (though Sluggish Shroom is pretty blatantly unbalanced), and board design is strong enough that the Orbs aren't being used as a crutch (the fact that certain Orbs are limited to certain boards is testament to this).
Those boards themselves are something of a mixed bag. You have two standard designs in Towering Treetop and E. Gadd's Garage, though the latter sadly ends up feeling pretty uninteresting; it's a case where, on high-end play, the board quickly becomes a solved puzzle, and there's little room for political intrigue between players. But this game is also one of the first in the series to lean into pure gimmick boards, where the mechanics behind Star acquisition change up. You have Faire Square, which had a fixed Star location but variable cost and room to buy multiple Stars; Snowflake Lake, where Stars must be stolen from other players; Castaway Bay, the series' first linear board (depending on how you qualify the first game's Eternal Star); and Clockwork Castle, a back-and-forth chase where you track down DK for Stars during the day and flee from Bowser at night. Of these, Faire Square and Clockwork Castle are pretty solid experiments (though the former's prone to runaway victories), Castaway Bay is surprisingly excellent, and Snowflake Lake flat-out sucks. I have a memory of playing Snowflake Lake with my mother when I was a kid; we'd decided to do a 50-turn game, and we were about 38 turns in when my mother landed on a Piranha Plant space I'd set down and lost hundreds of coins she'd accumulated (since, given the nature of the board, there wasn't much to do with money besides amass it). Felt like an extremely hollow victory.
Since I've spent so much time with this game, I can speak to its Single Player offerings. ...Solo Mode's okay. Mostly an excuse to play a buncha mini-games and grind out Stars for the game's various unlockables (mostly Toadette and Clockwork Castle). For that purpose, it's not bad, but don't expect much more from it. Of the three boards, Thirsty Gulch is fine but short, Astro Avenue is dastardly and counter-intuitive for the purpose of grinding out Stars, and Infernal Tower is the only one you should be playing. Always try to hit that top Happening Space to keep play going indefinitely; given how easy Sluggish Shrooms are to farm, that shouldn't be a problem whatsoever.
Also, to briefly touch upon the GameCube Mic here - it's absolutely a gimmick inclusion, but it's kind of cute for a bit of variety. I definitely think its use here is better than in Mario Party 7, since 6 had 3 different mini-games instead of 1, and they have a low chance of unobtrusively replacing 1v3 mini-games instead of being their own space. If you happen to have a Mic, it's worth trying out for a little bit.
If you're looking for the best Mario Party of this era, I'd point to 7 these days. But 6 is a solid runner-up. Like I said, it wasn't as good as I remembered, but it's not bad, and worth exploring here and again. Probably your best bet for a "middle of the road" entry in the series.
While not my first Mario Party, this was the main one I played as a kid, and easily the one I've sunk the most time into. I'm sad to report that it's not as good as I remembered upon revisit. It's still generally solid, with the Day/Night system allowing for some interesting experimentation within the boards. The Capsule system from 5 has been cleaned up into the Orb system (though Sluggish Shroom is pretty blatantly unbalanced), and board design is strong enough that the Orbs aren't being used as a crutch (the fact that certain Orbs are limited to certain boards is testament to this).
Those boards themselves are something of a mixed bag. You have two standard designs in Towering Treetop and E. Gadd's Garage, though the latter sadly ends up feeling pretty uninteresting; it's a case where, on high-end play, the board quickly becomes a solved puzzle, and there's little room for political intrigue between players. But this game is also one of the first in the series to lean into pure gimmick boards, where the mechanics behind Star acquisition change up. You have Faire Square, which had a fixed Star location but variable cost and room to buy multiple Stars; Snowflake Lake, where Stars must be stolen from other players; Castaway Bay, the series' first linear board (depending on how you qualify the first game's Eternal Star); and Clockwork Castle, a back-and-forth chase where you track down DK for Stars during the day and flee from Bowser at night. Of these, Faire Square and Clockwork Castle are pretty solid experiments (though the former's prone to runaway victories), Castaway Bay is surprisingly excellent, and Snowflake Lake flat-out sucks. I have a memory of playing Snowflake Lake with my mother when I was a kid; we'd decided to do a 50-turn game, and we were about 38 turns in when my mother landed on a Piranha Plant space I'd set down and lost hundreds of coins she'd accumulated (since, given the nature of the board, there wasn't much to do with money besides amass it). Felt like an extremely hollow victory.
Since I've spent so much time with this game, I can speak to its Single Player offerings. ...Solo Mode's okay. Mostly an excuse to play a buncha mini-games and grind out Stars for the game's various unlockables (mostly Toadette and Clockwork Castle). For that purpose, it's not bad, but don't expect much more from it. Of the three boards, Thirsty Gulch is fine but short, Astro Avenue is dastardly and counter-intuitive for the purpose of grinding out Stars, and Infernal Tower is the only one you should be playing. Always try to hit that top Happening Space to keep play going indefinitely; given how easy Sluggish Shrooms are to farm, that shouldn't be a problem whatsoever.
Also, to briefly touch upon the GameCube Mic here - it's absolutely a gimmick inclusion, but it's kind of cute for a bit of variety. I definitely think its use here is better than in Mario Party 7, since 6 had 3 different mini-games instead of 1, and they have a low chance of unobtrusively replacing 1v3 mini-games instead of being their own space. If you happen to have a Mic, it's worth trying out for a little bit.
If you're looking for the best Mario Party of this era, I'd point to 7 these days. But 6 is a solid runner-up. Like I said, it wasn't as good as I remembered, but it's not bad, and worth exploring here and again. Probably your best bet for a "middle of the road" entry in the series.