Bad:

• Frostbite (3) - tug of war = spawn camping, snowballs, recon footsteps.
• Downtown (5) - too many spikes, recon footsteps.
• Avenue (3) - snowballs, recon footsteps, super easy spawn camping.
• Stadium (5) - silly layout, too many walls.
• Gardens (3) - okay layout, but hard to reclaim home points. Small base entrance results in easy spawn camping.

Okay:

• Mines (3) - okay overall, but home points are hard to reclaim.
• Reactor (3) - okay but a bit easy to spawn camp.
• Furnace (3) - Shadowfire is a bit annoying, easy spawn camping.
• Facility (5) - nothing interesting but nothing bad about it. Spawn camping is rare.
• Ruins (5) - boring but not bad

Good:

• Forest (3) - double spawn entrances, many paths to take.
• Ramparts (5) - good design where strategy comes into play more than it does in other stages (where to go, which switches to trigger, etc.)
• Necropolis (5) - terrific design with hard to camp points, an interesting mid point, as well as a nice change of pace due to the path between home points being closed at the beginning but eventually opening for quick assaults on the enemy team's point.

Yes, but then everyone would have to make their lists best to worst instead of the current worst to best :P

Bad:

• Downtown: Way too big for 6v6, snow causes lag, CPs are too far apart for strategy, and Stun spikes slow down team movement and overall game flow to a boring level.
• Stadium: Isolated points in the bottom corners make for ignored points that usually get solo capped. Also the combination of very narrow choke points and huge open spaces means lots of team stomps due to bad positioning - either a team getting murdered trying to run through a choke with the other team standing in a concave on the other side, or one person holding off an entire other team by abusing the chokes and heal pads, especially in T2 and T1. Also too big.
• Facility: Way, way, way too big for anything interesting to happen. Also no unique map features/hazards make it boring, as well as long hallways and isolated points. It reminds me of Clockwork tunnels, which I hate for the same reason.
• Avenue: Vertical narrow walkways mean you can always get ambushed, and there is overall very little cover on the southern side of all three points. It's also very easy to spawn camp.
• Gardens: The chokes are too narrow to be rushed and too easily defensible by haze bombs or camping gunners on the lower points. It's impossible to hold the top/middle base because there is absolutely no cover and many entrance points.

Okayish:

• Frostbite: When this came out I thought it was terrible, but most of the newer maps are even worse. Main problem with this one is that it's almost impossible to flank because of the single-path layout, which means you usually just smash head-on into the other team all game long. It's also easy to spawn camp, but at least it's unique. Also snowballs are surprisingly useful.
• Forest, Reactor, and Furnace: These are the "standard" maps. Nothing too good, nothing too bad. Reactor's top point is a little bit hard to take, and furnace's temporary walls can lead to interesting strategies. The middle of forest is completely useless.

Good:

• Necropolis: The large base makes it very hard to spawn camp, the points are far enough away to prevent everyone spamming one point and close enough so there is near-constant action. Flanking is possible and effective because teams rarely cover both the bottom hallway AND the top middle point at the same time. Spam is also fairly ineffective on this map because it's fairly easy to just go around someone if they're trying to cover your screen with balls of electricity. All the points have enough cover to enable 2-3 people to defend them effectively, but enough open space to allow for duels and maneuverability.
• Ruins: This map always produces interesting games, especially in GvG, because of the map layout. The fact that the top lane is isolated from the bottom lane makes it so that teams have to dedicate to one side, making it a good strategy to stall a team in one half of the map while the rest of your team runs to the opposite lane and caps all those points. The low walls around points make supporting a teammate standing on a point by gunning viable, and still allow enough open space to fight in big 4v4s or 6v6s. The chokes are also wide enough (or close enough together) that bomb camping is mostly innefective. It's also only somewhat effective on points because there is enough space to maneuver around the bombs and get at the bomber, but a skilled bomber can counter that.
• Mines: The best 3-point map. If all the barriers are left up, the map can become very chokey and campy, but if you open them it becomes much easier to travel between bases. The heal pad in the middle of the map provides and additional objective point to draw a team's attention, even though it can also be used as bait to keep teams occupied while your team caps. All kinds of play are viable here because of the varied map geography (chokes, open space, vertical hallways, horizontal hallways, etc) Much like Necro and Ruins, it is also actually possible to defend a point, but also possible to attack one. Only downside, the base entrance is small and if a game gets too one-sided, it can turn into a campfest.
• Ramparts: The best 5-point map and the best map. The unique layout is great for attacking through every possible angle, the points on your team's side of the map are all close enough to spawn to allow for defense as well as healing and massive teamfights in the fairly enclosed areas. The easiest points to take on each side also have the great bridge along the bottom which teams often forget about, which can lead to surprise attacks as well as quick escapes and reinforces as well as epic 1v1s on the bridge. The top corner points are fairly isolated by walking distance but are very easily accessible with ranged weapons, which combined with the gate leading back to the team's home base leads to some of the most interesting fights in LD. The bottom point is a bit far away from everything else and sometimes goes forgotten, but even though this map is big its rush distances are surprisingly short. This means if one team does forget about that point, 1 or 2 people can go resecure it. The wide-open space in front of the bases and the gigantic vertical hallway leading down to the bottom point allow for surprise attacks (because of the vision and lack of defense) but also allow for escapes because of the lack of obstruction. And above all, it's fun to play on. <(^_^)>

*looks at everyone else's post*
Oh god, I wrote a lot.

...Do I win