The worst one was Nvidia driver. I tried to install it manually as the Linux version was giving me black screens. For start i had to learn of how to execute the *.run file. After finally executing it, i had to learn how to root and how to locate the file trough commands. After that, i wen through a long list of errors like: 1)nouveau driver was already running; 2) the command to disable nouveau driver didn't work; 3) the kernel command to disable it didn't work too (something similar to rd-blacklist:nouveau) 4) During install process, a pre-script could not be run; 5) after that, a second "kernel command" installed by the driver didn't work; 6) i had to unninstal it, 7) reinstall, 8) got black screen. After that i could not disable the driver anymore. I tried nvidia.modset=0, apt purge nvidia and others. The only solution was to reinstall kubuntu. I had to do all that without even knowing where were the commands at the start, or how to inset kernel commands. So it was really frustrating.
After that, i gave up of nvidia driver and decided to test others installers. I decided to start with something i was familiar: an antivirus. I tried ESET and faced the same problem, now starting with a *.linux file, that i could not make easily run. So i decided i could not go further having to learn each detail just to face another problem in the "next curve". That's why i believe Linux really has to move into a more friendly use. That probably why Linux Mint is getting so famous nowadays.
It's a pitty, as i really liked Kubuntu. It was light, fast, beautiful and fun. I'll certainly give it another chance in the future.