Correction~ the second line ~ THEIR fault

I agree with the comments above. Although I think Schotish English accent is the hardest but it is not there fault. It is hard for me because I rarely listen to them. I have spoken once to someone from there and the conversation was desaster. I like American accent  because it is flat and beautiful. Again thanks to the movies. I am tired of my accent. It sound hard to get ride over it. It is Arabic-English accent with hard rolling rrrrrrrrrr :)

I am from India and I find Australian Accent very fast and irritating to my ears. Though a lot of them speak quite good, I might have probably got used to Neutral-Indian-or British accent  so much.

The South African accent is a bit different. I watch international rugby and I understand all the different english accents, but find the South African accent unusual.

No accent is inherently more difficult than another.  They are just a matter of different pronunciation rules.  That said, I've never heard a non-Australian get the Australian accent right, nor have I ever heard a non-Bostonian get the Boston accent right.