蚊に刺されるほど嫌なことはないって英語でなんて言うの？

Bees sting, mosquitos bite, so the correct verb is bite.
There is nothing I hate more than being bitten by mosquitos.
You can also use detest, or loathe, in place of hate.

1. My biggest pet hate is being bitten by a mosquito.
   If something is your biggest pet hate then it means that
   it is an action/occurrence that you loathe/dislike intensely.

   2. There is nothing I detest more than being bitten by a
      mosquito.
      To detest something means having a strong loathing/dislike
      or aversion to something.

To not be able to stand something is used to express when you really don't like something. So the expression "I really can't stand being stung by mosquitoes" is a useful expression in this case.

When you want to explain that there is nothing you hate more than being bitten by mosquitoes; then you may say this in the following:
-There is nothing I hate more than being bit by mosquitoes

Other ways to say the same thing:
-I really hate being bitten by mosquitoes
-Being bitten by mosquitoes is the worst

If you wanted to explain that there is noting you hate more than being stung by mosquitoes, you could say either of the following to express it: "There's nothing I hate more than being stung by mosquitoes" or "I really hate the feeling of being stung by mosquitoes". Both these statement summarise your point of view.

You can say either of the following:-

1. I absolutely detest being stung by mosquitoes. If you absolutely detest something it means that you hate it as much as you can hate something.

2. There is n nothing I hate more than being stung by mosquitoes.

Your example is absolutely correct and I think it is the best way you can say it. There is no huge difference between using "getting" and "being". You will get the same meaning, although, the actual translation of these words are different.