so what is also more challenge based is
ring0team:
https://ringzer0ctf.com/

if you are interested in binary exploitation, there is:
https://overthewire.org/wargames/

if you want to checkout some nice videos on differnt topics including hardware security, checkout lifeoverflows channel:
https://www.youtube.com/channel/UClcE-kV...cjYwcpfj9w

regarding Hackthebox:

when i started HTB, my first box was a metasploit one but got me really hooked and was my entry to pentesting.
Never used metasploit too much. in the early days it was sometimes a question of the right wordlist
but it is not the case anymore and sometimes you have realy fancy privesc's to do :) .
To get some good methodology on approaching a target, there is a youtube channel from a user called "ippsec" who makes walkthroughs on retired boxes.