Back then when I started to learn English I didn't know about these accents things. But recent days I have come to understand that I learned a lot of American English. So I didn't kill my time listening or reading to British English articles.
But about three month now, I have got to love British English. To be honest, I don't get tired when I'm listening to British people conversations. I really enjoy it, that is not what I wanted but now I have to go where my heart direct me.
I feel like goosebumps all over my body when I listen to British English.
The different varieties of English aren't really that different to be honest. If you only study one type of English and go somewhere else, you will still have no problems communicating (as long as you stay outside of Scotland or the southern US anyway, where the local accents are much more different). The different types of English are really more like different accents than different dialects.
Pretty much all media includes a wide variety of accents. With the exception of movies meant for very small children, I don't know a single movie in which all the characters speak just one accent. There's a running joke that Disney always casts people with American accents as the protagonists and people with British accents as the villains!
There definitely are noticeable regional differences in English, but these differences are rarely big enough to hinder understanding. I recommend you just expose yourself to as many different accents as possible and not worry about which type of English you end up using. English speakers from different countries never have to switch to a "standard English" (not that there is such a thing) like speakers of other languages do. We can just talk normally and understand each other just fine.
Www.forvo.com is a good place to hear how people from different places pronounce different words.
Jmat has made a number of excellent points here, among them the fact that standard American and standard British English are really not that different from each other. The grammar is the same, and probably more than 95% of the vocabulary is the same. The writing is also identical, apart from a tiny handful of spelling differences that really don't matter in the slightest. And yes, we always know whether someone is speaking British or American English from the accent, but even that isn't enormously different - in general, some (but not all) vowel sounds, the sound of the 't' between vowels and the 'r' after a vowel. And that's about all. It's the same language, and we can always understand each other. Nobody needs to make a choice.
By the way, do you mind if I point out a difference between two phrases? In your post, Seif, you said 'I didn't kill my time listening...' What you should have said was 'I didn't waste my time...'. Or in other words, perhaps you didn't have a lot of time to spend on English, and you decided that it would be more useful to devote this time to US English. The phrase 'kill time' (note that there is no 'my' in the phrase) when you have too much time on your hands, such as when you are waiting at the airport for a delayed plane, and you play a game or something to 'kill time' and make this boring period go more quickly. As you can see - this is has a completely different meaning.
English is a fascinating language, however you pronounce it. Enjoy your studies!
Depends on the purpose for which you are learning English. Generally, British English is considered more correct and "proper" as Amercian English varies a lot and is often considered incorrect in places. Why not learn both. It will expose you to two different cultures, accents, and ways of expressing yourself. Just consider them as two dialects of the same language.
I prefer British English, it sounds really good and I learnt this one at school anyway. But if the most important thing is to have an accent that is easy to understand, I recommend Canadian English, they speak really clearly. As for the American accent, I have realized that each person speaks differently, so you may understand some of them easily, while understanting others may be a bit harder.
British accent sounds more interesting and awesome, however sometimes it's hard to understand. In my particular case, I'd pick to learn American English since it's more useful for my career. Almost all the clients I have to deal with are from there.