Which airline is best to work as a flight attendant in? Qatar Airways or Kuwait Airways?

So I got accepted in both and I can't makeup my decision, I'm gonna work as a cabin crew in one of them, which airline is more flexible and offers the best salary? I don't know about Qatar but Kuwait Airways salary as a cabin crew is 2.55k tax free including a furnished apartment and it goes up depending on flying hours. Anyone can help?

Only you can make that decision.
You need to consider where you'll be based at upon completetion of training (less than 50% complete training)
Pay isn't everything
I'd choose the airline that starts training the soonest so if you fail, you can try again with the other airline

Look at the potential benefits package and decide from there

I know that with Qatar, you sign a two-year contract and they do furnish housing in Doha. However, I have also heard that privacy is non-existent, job security is not good and they are very controlling - turnover rate tends to be high

Where will you live? That's a big part of it. There's a lot more going on in Doha that Kuwait and its more modern too. But you won't be allowed to enter UAE, Saudi, Egypt etc at the moment if you are a Qatari resident due to the ongoing diplomatic crisis between those countries. That might be annoying for you as it means no weekends in Dubai etc. Doha is warm year round but it gets very cold in Kuwait in winter. So that may be a factor too.

Obviously you have to make your decision… That being said, I would advise Qatar airways only because they operate off a 'you get what you pay for' business model, and your least likely to have to deal with problem passengers as people who fly Qatar generally are willing to put up with paying their fares in exchange for a peaceful relaxed flight.

You say you've been accepted by both.
So how come you only know about the salary and conditions for Kuwait, and not for Qatar? You can't possibly have been 'accepted' without being informed of your salary and conditions.