Boxing is the only martial art my two lower back herniated disk allow me to practice nowadays.
Allow me to present my opinion.
Ive practiced TKD when i was a teenager because i had natural flexibility to kick. --> its utter trash. TKD people dont spar and have no idea how to deal with close combat, they are practically laymen. Sure, a head kick is fast and dangerous, but thats the only one trick pony they have.
Ive done Muay thai some years after: brutal, intimidating, ive realized how fucking WEAK and vulnerable ive been all that time. It was a harsh reality check. Getting hit is painful and not funny at all.
(as an untrained average joe, if you imagine a potential street fight you might think you just dodge and do this, and that etc. Practicing any decent martial art will make you almost cry thanks to the reality check lol)
BJJ: same feeling of vulnerability i had when i did Muay thai. Amazing martial art, you gotta use your brains, and i consider it the hardest martial art to learn. You gotta study, think, feel it. Fucking hard.
Unfortunately , both BJJ and MT made me fuck my lower back for life, so i must take good care of it and stay away from both sports.
My opinion about boxing: every training session makes you dehydrate. it requires good conditioning and you spar everyday. You get accustomed to not flinch at all and getting is hit is not longer that nightmare from before. It is far superior than fake trash like aikido, TKD , etc ; but i just cant see how a boxer can beat a tough muay thai fighter.