First thing is to decide what kind of sound you like. It's especially hard if you haven't heard any headphones for reference. The most important difference between similar quality headphones is basically the sound signature.
Also You should narrow down what kind of environment you're going to listen to those phones. Outside or inside with/without amp noisy environment or need for silence. Sitting down or walking.
Then you have to set a the price range
Then you have to guess which sound signature will be more enjoyable to you at your price range.
Guessing what sound signature you like without hearing is a guess. You might get it right or wrong. Unfortunately some of use don't have an easy access all the headphones so we have to rely on the forum and guessing.
That why we often ask what type of music you will listen to.
Because some sound signature are more suitable for certain type of music for a large portion of user.
But then each person is different so it might not perfectly suite your taste. So in the end you have to try multiple headphones and try to find what kind of sound signature you like most.
Words description can only go so far. But that the best we can do on a forum. By reading a lot of info you can get a relative idea of what the sound signature is like and choose the headphones accordingly.
Good luck
IF you haven't follow what I said
Well just tell us What your price range. How your going to used them and what type of music you enjoy and will do the guessing for you.
PS. Forget about spec they are pretty much useless for anything beyond the very basic.
