There are a lot of GTA 5 custom maps. Most are forgotten. The ones that matter are the ones that pushed the scene forward in a specific way - tooling, ambition, design, or community impact.
Companion to the most popular custom maps page.
Liberty City for V
The most ambitious project in the scene. Years of work. Brought GTA IV's Liberty City to V. Even in unfinished form, it changed expectations of what custom maps could be. Covered specifically on the Liberty City mod page.
Vice City Remastered
The 2002 game's city, in V. Long-running project. Exists as inspiration even where incomplete. Covered on the Vice City Remastered page.
Major MLO collections
MLOs from named creators that reshaped how RP servers operated. Specific names depend on the marketplace; the impact is on the broader ecosystem.
What 'mattered' actually means here
We don't rank by downloads. The maps that mattered are the ones that taught modders what was possible, that shipped first, that defined a sub-genre, or that survived as long-running community projects.