If you have to purchase/download Logic from the App store then you can only install 9.1.8 as that is the only version available there.
By the looks of what you listed, this will be your only choice unless you can find/purchase a Logic Pro Studio 2 Upgrade Boxed set which do appear every now and again on places like eBay.
Once you have or if you already have the Logic Pro 9 / Logic Studio 2 boxed set then you could try 9.1.5 first via this link...
http://support.apple.com/kb/DL1519
If all goes well, which it should with that version... You could then clone your System HD using CCC or SuperDuper! and then upgrade to 9.1.8 and make sure that all works well too. If so great.. and if not you can roll back to 9.1.5 using the clone you made...
Additional Notes:
Logic 7 and Logic 8 will not install in ML.... (though there are some hacks around to get L8 to install, but frankly I wouldn't recommend them as some people have reported stablity issues afterwards)
The ideal combo with Mountain Lion would be 9.1.8 but some people have issues with that version and a form of GUI lag that occurs hence the suggestion of trying out 9.1.5 first if you can... as that was probably the most stable version of Logic for the vast majority of users (Albeit usually with Snow Leopard I might add) However, many users have no issue running 9.1.8 and ML.. so it's worth a shot too, if you have the choice.
