pick one. you'll end up with a favorite you use all of the time anyway, and sooner than you expect--after rebooting into this-or-that constantly to run something specific that's set up in it, or when you get tired of duplicating efforts a half-dozen times in all of them. you'll soon forget which distro has which app set up which way.
the rest in VMs so you can be familiar with their package management, system layout, and such. You can spin 'em up, destroy 'em, run them simultaneously, try out a new package or application or configuration, whatever; and in that process, mess shit up (it happens) without any damage done to your daily-use OS.
you mess up your octo-boot system and it won't boot up. you need answers. your only pc is on vacay. what are you gonna do? use your phone's tiny screen and poke questions or searches into google or stack one letter at a time? nah, mate. don't make it difficult when it don't need to be.