but those are so expensive and not that much better to be honest
Just pointing it out that these filter lands serve a very different purpose. Shadowmoor/Eventide filters can make coloured mana into more coloured mana. In a pinch they produce colourless. The Odyssey filter lands act more like Signets: they need another mana source (i.e. useless as your first land) but they can filter any mana into their colours.
Use cases:
- Shadowmoor/Eventide filters will help a deck pay for double, triple or quadruple pip costs. Example: Necropotence in a three colour deck.
- Odyssey filters will help a deck pay for multicoloured costs with a lot of different single pips. Example: casting spells in a Niv-Mizzet Reborn deck.
Most of the time people want to cast their multiple pip heavy haymaker spells on curve so the Shadowmoor/Eventide filters make more sense. But when it comes to WUBRG, for example, it helps to be able to produce two coloured pips out of a colourless source.