A map that offers balanced gameplay. The actual ingredients aren’t set in stone. I wouldn’t suggest to put roofs against arty on Nameless Tower, but it’s a good idea to have it in Powerplant for example. My problem tho is that Targem doesn’t seem to understand what makes a good map. They had a 10/10 map with bridge when they gave it a 3rd path, they ruined it by making the bridge destructible 3 months later.
So far the only good maps IMO are Powerplant (great map for long range, great map for short range, great map for flankers, great map for arty, just a great map), Bridge w/o destructible bridge (The map used to be campy af but with arty becoming relevant, it was perfect. Now that the bridge isn’t an option anymore, lots of builds just get f*cked extra hard, while porcs can 1v4 most teams in the ramps), and maybe Quarry (The ledges make it hard for dogs, but the map is small enough that mid-range weapons aren’t just sitting ducks for scorps on the cap. Spawns aren’t ideal tho, a bit close and you’re exposed as soon as you get out of spawn) and Clean Island (The acid isn’t too bad and the map offers good opportunities for everybody, hovers, snipers, melees, porc progamers, etc).
Canyon is hmmkay, a bit tiny tho. 10s into the game you’re already swimming in Porcs or getting torched by a Flash Firebug gentleman. C-17 isn’t horrible, but it really suffers from being just a giant open field with boxes dropped on it. There’s no real interesting gameplay opportunities here, no verticality, no ledges, no one-way paths. It’s kinda balanced, but also very very very boring.
On the other hand, this game has maps like Crater (oof), Naukograd, Nameless Tower, Fortress, Rock City… There’s honestly more maps I hate than maps I like, and we’re at a point where I’m happy to roll Factory. I think it’s an horrible map, but also above average for XO 
One thing to keep in mind is that the multiplayer games I grew up with let you chose the map you’d play. CS and Quake 3 were full of bleh maps, but you could just spam de_dust2 and DM6.