I'm really interested in both Korean and Mandarin and I have really hard time to decide which one to learn first. When it comes to the question which one I love more to learn, I can't really say because I like both.

Because both languages are really time-consuming, I want to decide wisely and that's why I ask whether there are any linguistic reasons why it'd be more beneficial to learn first Korean and then Mandarin or first Mandarin and then Korean? For example, I have already heard that the advantages of going from Korean to Japanese are greater than the other way around because there are more sounds in Korean than in Japanese and after learning Korean pronunciation, Japanese pronunciation is much easier. Reportedly Korean also has more politeness levels, more tenses and more conjugations than Japanese. I love challenges and that's why I'm not afraid to choose the hardest one but I want to do a smart decision and that's why I'm asking the question. Could it be a good bet to learn Korean with Korean hanja characters, for example, because then learning Chinese could be easier or is the other way around still wiser?

All kind of experiences and advice are welcome.