What option will generate fewer aquifers in world gen?

3 Options:

The Lazy Newb Pack way: Just click the Aquifers button after running lazy newb pack.exe

Changing WorldGen Settings: Courtesy of Chrissi from the bay 12 forums

To actually answer the question.... yes, you can render a world with significantly less aquifers (I have done it) by increasing the minimum elevation in the parameters. Try 20 or 40 or something. It also reduces oceans, but oceans are what cause aquifers in the first place.

Obviously this has other side effects on world gen like making the world more mountainous and making oceans smaller/nonexistent depending on how high the minimum elevation is. There is no option to just turn off Aquifers in the advanced mapgen, although I believe some mods do have that option.

Editing the raws:

Text editor (All operating systems) Find the files in Dwarf Fortress/raw/objects (new world) or Dwarf Fortress/data/save/regionNN/raw/objects (already saved world). Open the three files with a text editor (e.g. Notepad). (inorganic_stone_layer.txt, inorganic_stone_mineral.txt, and inorganic_stone_soil.txt) Use Edit->Replace, and replace [AQUIFER] with (AQUIFER). (Use 'Replace All'). To restore the tags later, do the same in reverse. (Replacing (AQUIFER) with [AQUIFER]).