If you have a new LG G3, it is at the 12B software update and Stump won't work. You have to use the LG flash tool to revert back to the 10B software. Towelroot does not work on the LG G3. I never had it tell me anything beside my device was not supported. If you are new to this root and ROM stuff...TAKE A FEW DAYS and READ.
Illusion is as far as I'm concerned the best deal going. But unless you take a breath, read, and have some idea why you have to do what you need to do, you may well wind up with a brick.
The reason Stump isn't working is likely due to 12B software. Once you get the Stump appliqued, then you need to apply TWRP via Bump. Then you need to backup, then you download a ROM and use TWRP to install it.
If you want to root and flash ROMs', the cardinal rule is ...Do not ever, ever take a OTA update. When you get the official 5.0 OTA, root methods will almost certainly be blocked.