Here’s a list of the best perks to select from levels 11 to 20 with the Leveling Build Guide in Fallout 4:
Level 11 – Idiot Savant 2
Level 12 – Chemist
Level 13 – Gun Nut
Level 14 – Nuclear Physicist 2
Level 15 – Hacker 2
Level 16 – Locksmith 2
Level 17 – Lone Wanderer 2
Level 18 – Scrounger 2
Level 19 – Bloody Mess
Level 20 – Bloody Mess 2