Both languages are very hard to learn because the writing is nothing like ours, although I would say that I found Japanese was easier as I learned it after Chinese and I found that helps you.
Japanese is easier to learn. Only because Chinese is completely not easy. The japanese language has an alphabet, is phonetic (??) aka when you say Arrigato people know exactly what you mean. Chinese has 100s of different dialects, all requiring exact intonation otherwise people will not understand you. As far as writing Chinese, you can forget about it if you are doing it for fun. Each word in the language is represented by a character, not by use of an alphabet.