...what is the main thing you take into consideration?

I either google lots or just try it cos it's something different! Usually a combination of the two!

I usually either stick to something that has worked for me in the past. If I try something new it's because I have seen it work for someone I know personally-a friend or family member.

I do my own personal research. I tend to avoid meat, carbs and sugars. Those are the three evil culprits in the world of food. You can't trust anyone. You have to spend the time learning about food and nutrition yourself.

I honestly Google like a mad man! I'm pretty good at research when I have the time. I agree with dialectic, if you really wanna lose serious weight, avoid those three! Or at least cut back on all of them dramatically.

I done it before and alwsys works (atkins)

I usually choose something that has worked in the past but now I'm eating as clean as I can and trying not to be too restrictive with calories as I want it to be a lifestyle change for the long term rather than a diet

I use what I know works. I track protein fat and carbs when I am in a leaning down phase, when I get there, I tend to eat intuitively. If the abs start to look soft and fuzzy, I monitor a bit more closely.

Not a diet, but just using common sense and some nutritional knowledge to meet my goals.

I research the method. I mean everywhere find out everything I can to see if it's the diet for me. I make sure it's fool proof. I don't try anything to "new" or without some kind of tests or research done on it.

Choosing a proper diet is not only essential for quick weight loss but it has other benefits:
If you have a proper diet plan you will not starve and it will in other words make you lose weight properly
cheers