I can certainly deal with your first example. The other two sound like elevator music to me. After your post I read a little bit about Jazz and it comes in various forms indeed. So, to specify a little bit, I would say that I'm not fan of Jazz with trumpet instruments.

I can't stand overly saccharine children songs and ghetto noises in equal measure.

New Country
n
(Music, other) a style of country music that emerged in the late 1980s characterized by a more contemporary sound and down-to-earth rather than sentimental lyrics

New Country has simpleton lyrcis about pick up trucks and family life. They don't speak to anyone with an IQ over 80.
Unlike singer/songwriters like Hank Williams Sr. and Johnny Cash whose lyrics and ballads are powerful and offer insight and reflection.

Any genre that includes electric guitar. (*especially* heavy metal, which is so pervasive that the topic titled "the metal thread" doesn't seem to say anything about actual metals like iron and steel.)

I would rather listen to aleatoric or other strange modern art music, or to Pokemon glitch music, than listen to electric guitar.

(Note that this includes synthetic sounds that mimic the electric guitar. One of the reasons I like NES chiptune music is that the NES sound chip can't mimic the electric guitar, unlike, say, the Sega Genesis soundchip.) Case in point:

Take Dave Brubek's Time Out album. Take any part of that album that is in 4/4 time, and it just sounds dull and uninteresting; it's the "boring" sort of jazz. On the other hand, the whole selling point of the album is unusual time signatures and rhythms, and the parts that are in such time signatures are far more interesting.

Given the amount of distaste for rap here this might not be popular but I love the explanation Killer Mike gave Joe Rogan while talking about his love of old outlaw country music:
"There's something about the Allman Brothers "Midnight Rider" and "Whipping Post" that's radically different than you just singing about your Ford and, you know, rafting on Saturdays with your chick."

I agree with the new country stuff, every time I hear it at work it just sounds like idiot music for rednecks. Although "least favorite" would be overselling it, since it is not a favorite by any means.

Anything that can be described as a "hit" really, hyper-capitalist, overmarketed dredge that I've read someone perfectly describe as "social pleasantry" than appreciated as art. It is offensive in its inoffensive-ness and reeks of selling your soul for money.

gospel and gangster

Least favorite... now that threw me for a loop. Gospel, R&G, Rap, Regge, followed by Classical, then Jazz

What. The. Fungus.
Just, meditate on this and repent.
One thing is not liking it, another is stating it's random. Improvisation doesn't mean randomness.

Back in line: I can't suffer reggaeton and trap. The first is a largely meaningless abomination, while of the latter I completely dislike the sound.

About country... it depends. Most is aimed to central US farmers stuck in the 1700s and I doubt anybody else could like that, but there are egregious examples of artists stepping way above that.

Jazz, dislike pretty much all it's forms.

well for me it is very random , the problem is not even that mostly , but it gives a feel of those warm pools where the old people laze so i associate it with just waiting to die of old age or nursing home the elevator music analogy is good also

I do tend to dock points for lyrics I can't understand unless they're quite literally in another language.

As for Country, I've already shared my beef, grain, corn, and cows with it. This reminds me of a qualification: Literally worse versions of classic songs.

Mariah Carey, you've tained more than a fair share of Christmas Songs. Kindly stop.
I have some terrible news.
I'm honestly surprised with the suggestion of Gospel, I'd think of it as a largely dead horse genre.

Rap, hiphop, techno/house/trans etc., pop, country, blues, disco.

[Interestingly I quite like jazz, but don't like blues at all. Maybe because jazz is quite "out there", whereas blues is such a cultural thing.]

These are easy for me to avoid though, so I don't know if I can call any of them "the worst".

The worst one therefore, has to be Nu-Metal, since I can't avoid it on the rock & metal stations I listen to, magnifying my dislike for it.

Of all obnoxious things best left forgotten... Here's hoping it flops.