Is anyone else tired of hearing about rhotic and non-rhotic accents? As a native speaker I barely even know what those words mean (much less have ever used them or heard them in conversation) and I can only imagine how confusing such discussions are for non-native speakers. In fact, accents are something that by their nature are nearly impossible to describe with any clarity. 

"If somebody were to speak words that have the letter "R" which is not followed by a vowel, then this person is able to speak more quickly and effortlessly with a non-rhotic accent than with a rhotic accent. In this aspect, British English (Received Pronunciation) is better than American English (General American).

However, if somebody were to speak some words that have the letter "t" which is in the middle or end of a word, then this person is able to speak more quickly and effortlessly by flapping the "t" into the letter "d" sound instead of clearly and precisely pronouncing the "t" sound. In need this aspect, American English (General American) is better than British English (Received Pronunciation)"

Incidentally, <em>both </em>of these are done in Australian accents.

No accent is inherently more difficult or easier than any other accent. There is nothing about any style of pronunciation 'per se' which would make it any more or less accessible to the learner.

When it comes to passive skills, it is simply a case of what you are used to. You will find it easier to understand the accent which you have heard the most : if you are accustomed to hearing British English, you will find that easier to follow than American English; if you have been exposed to more US culture through the media, you will have less trouble understanding American English than British English.

As for productive ability, the accent you choose to focus on makes no difference, because first and foremost, you will speak with a Spanish accent. Spanish people encounter the same pronunciation difficulties - for example problems with stress and intonation, long and short vowel sounds, -sp -st -sl -sm sounds at the beginning of words - regardless of the variety of English which they learn. Choosing to learn Australian English rather than American, or American rather than GB.E, will not make English pronunciation any easier for you or eliminate any of these problems.

There is, I'm afraid, no such thing as 'easier' ( and certainly no such thing as 'better' - although students do often ask this!).  If you feel that you want to make a choice - and you really don't have to - just choose the variety that you prefer, or that you think would be most useful for you in future.

"Gid'day"?? ':)

American one was easier for me to get used to, because of watching many american movies...

I like how it sounds.