This is a very late response but I also wanted to give you input - I'm a South Korean who's been learning Japanese for 3 years.
I've lived in South Korea since I was 11 and I've been to Japan 3 times, and I speak native Korean and fairly fluent Japanese.
I personally think that learning Korean will probably be easier. Both languages have a fair share of words that root from the English language, so you'll start out knowing a lot more words than if you were to, say, learn Mandarin (which I also speak, and is definitely much more difficult). But here are the objective advantages that I think Korean will provide when learning for the first time as a foreign language:
1. The simple alphabet. Both languages have their own alphabets (which you probably already know), and with the exception of a few rules they are written exactly as they should be read and you should have not problem aside from the memorisation. However, Japanese has not one but two sets of useable alphabets - Hiragana and Katakana. Hiragana is used much more widely, with katakana mostly utilised for emphasis or for words that are taken from other languages such as English. In addition, Japanese uses kanji, the Japanese form of Chinese characters, which is an extra burden - not to mention the fact that a certain character can be read completely differently depending on the situation!
2. Honourifics. Both languages have honourific forms that are different from the casual / colloquial forms, as both countries have a sort of Confuscian culture that encourages respect for elders or those in high positions. Which means that whichever one you learn, you'll have to end up learning two rather different versions of the language. However, in this aspect Korean is definitely much easier to learn. Korean basically has two types: ban-mal (반말: non-honourific) and jondaemal (존댓말: honourific). Japanese does too, but their system of honourifics is much more complicated depending on the relationship between you and the listener or whatever other third party is involved. It's something that Korean used to have as well but shed a little over time, while it seems to have remained much more preserved in its Japanese counterpart.
Korean and Japanese have similar grammatical structures, but it's wildly different from English so it may take a while to get used to it.
Whichever one you choose to study, I'm confident you'll enjoy it. I recommended Korean to you because I felt it may be easier for someone to learn it as a second language, but studying Japanese is something I truly enjoy and I find myself making excuses to go back to Japan each holiday. What a beautiful country.
For either language, I think it would be effective if you used Korean or Japanese TV entertainment to help you get a grasp of the language. K-drama has become popular in recent days, which makes it easily accessible, and anime has already been around for ages. I've observed that my friends (who also learn Japanese) find it much more comfortable to start speaking the language when they've heard it being said so many times through anime.
Anyway, both languages and the cultures behind them are historical and beautiful and I'm sure you'd enjoy either one equally. I'd be happy to answer any other questions or to help you out in the process. (Or recommendations for stuff to watch. Haha)
Happy Language-ing!