If you are just starting with Linux use something easy like Ubuntu(easy mode, Great for starting). Then try Debian(Stable with little to no updates ever but more complicated), If you decide you like to compile things your self try Arch(For those who like to compile all their programs themselves). And it's really a rabbit hole from their with all the different flavors. Linux is as secure as your understanding of it. The more you know the better you can close the holes. But at the end of the day Tech is Tech and if it is connected to the internet you will be vulnerable.