Similar to how the newer Manor has a contract system, guild houses should have a similar setup.

Currently, Guild Houses almost exclusively go to larger guilds that can more easily afford the house, but it completely locks out everyone else or smaller guilds from even trying.

Unless you have said houses, making use of guild crafting, shipyard, stables, etc are dead content

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So what I propose is a set rental system that takes from the guild funds at certain intervals

You can then either perform quests or have to be next higher guild size to unlock a bigger house upgrade 

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Other suggestions are welcome, I just feel the blind auction system is a bit dated and makes it so smaller guilds are left out on a ton of content