Nimbus Maze, is my favourite mana fixer as it literally gives you the mana you don't have. If you have islands but no plains, this can now give you white mana. Once you're set up and can create both your mana this can create either. It's not very good outside its two colours, but we're only playing two colours, so it's pretty good
Minamo, School at Water's Edge is a power house. Most likely we will use it to untap one of our legendary lands to multiply our mana, but even when mana multiplication isn't available it is pretty much an island, so it has no downside.
Karakas. Warning this is on the EDH ban list. My personal playgroup allows its use with the added rule that it cannot target opponents commanders. In this deck it is mostly used for mana and to defend our own creatures, we have a lot of legendaries and it is tricky to recur them from the graveyard in our colours, therefor this is one of the ways we can save them. If your playgroup does not agree to its use under the added rule simply replace it with a plains.
Nykthos, Shrine to Nyx is the first land that can create crazy amounts of mana. If your board state is descent this can create upwards of 5+ mana. And as an added bonus, it is never a dud it can always create mana, unlike the other crazy lands we have