Can you recommend a terrain generator?

Hi
I am looking for a realistic terrain generator that i can generate a terrain with and export it as .raw to import it into unity.
I have some choices but i would like to know what terrain generator you guys use. If you know one free or paid, better works on mac osx please post a link.

Dont know any native mac ones myself…

I use world machine on my windows PC.

There are prob ways to get it running on the mac tho.

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Can World Machine run on a Macintosh or Linux PC?

This is not officially supported, and there is no native build of World Machine available for these platforms.

Unofficially, many users have found that World Machine works just fine under Parallels or WINE. If you want to try: Double check using World Machine Basic edition that you can use World Machine successfully on your configuration before purchasing! Unfortunately no support can be provided on these platforms.
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Taken from their FAQ.

Vue can do this, and so can Terragen. However, you may want to look at the Asset Store for terrain generation tools. There are quite a variety. I’m using Terrain Composer in my project.