Hello wushujosh,

Talking about accents, I guess there is no final answer. I speak Southern accent. I must admit that there is a number of characters that sound more or less the same in the South, such as "s" and "x", "ch" and "tr", "d" and "gi".

Nevertheless, because the South don't differentiate the sounds very much, you will have an easier time with the tones, which I believe is the hardest thing foreign speakers have to overcome. While speaking Northern accent, you have to be able to clearly pronounce the 6 different tones, in the South, 5 is enough.

More than that, depend on who you are, formal or informal, outgoing or traditional, keep in mind that sentence expression is very different between the 2 (talking about spoken language here), with the North being very traditional and conservative, it is like you have to go through all the necessary steps during a conversation, no matter how significant that might be, while in the South it is more relaxed, more expressive, with lots of different kind of emotions being put into. So in that sense, I guess the South is a little harder, in terms of vocabulary and grammar, because there are just too many supplementary words and ways to combine them to be able to use correctly.

You really should keep learning Northen accent, because it's nearly the standard dialect in Viet Nam. Although Northern accents diverse in many regions but they're closer to standard dialect than the others in Viet Nam 

I'm primarily attempting to learn the southern dialect, because that's where my wife's family is from and most of the Vietnamese where I live in the USA are proud southerners. I don't really talk to my in-laws in Vietnamese, just Cantonese mostly, but they often speak to Vietnamese people so I want to understand what they say and getting better Vietnamese would help with my job of translation, too. Early on most of the materials I came across were northern, so I have had most of my listening practice with northern Vietnamese. As a result, sometimes I say things with a northern accent but use southern expressions. Now I've finally come across more southern stuff, partly as a result of using iTalki. I don't think there's a huge difference in which is harder, I think it's just a matter of getting more exposure, although having lots of language learning materials to teach the southern dialect would facilitate this.

 @Quang - ya I have a lot of trouble distinguishing the letters/word in the southern accent. too muddled.

@nhien - I dont particularly like the sound of the southern accent, I am learning the north because my girlfriend and her family are from northern vietnam. Many people speak the northern accent it doesn't seem to just be an ancient symbol :P  But I posed this question only as a curiosity to see what others are studying and why

Thanks for all your replies so far 

Generalizing, the North is way easier than the South. A lot of letters in the South sound alike (x and s sound exactly the same) so it will be fairly difficult to spell. 
If you know North you can easily convert to South but its harder vice versa, though i think it depends on the person.