Never tried both, really..Japanese is; with all respect, probably the most complicated language I've ever heard. the words just have so many different meanings! I'm nervous to try unless I'm absolutely sure I know the language because I don't want to unintentionally insult someone.
It's not just Japanese that has words with so many meanings. I mean, think of it this way. It's just like the English word "jam." There's jam as in jelly, but there's also jam as in the verb that means "to shove." For example: "I want to jam the sandwich into my mouth" is different from "I at the jam sandwich."
In any language, there are going to be a lot of words that have a lot of different meanings or translations. In fact, if you asked a student taking English as his foreign language, he would probably tell you that English is harder than his native language because of all the different ways to speak. Like, the bast tense of "run" is "ran," but the past tense of "jog" is "jogged," not jag or runned.
Besides, if you unintentionally insult someone, they will probably be able to recognize from how nervous you are that it's not your native language, and from what I understand of Japan, they would probably chuckle lightheartedly and politely correct you.
ANYWAYS, I'm not really one to comment, because I'm largely self-teaching through books and a few Android apps. It works for me because I can learn at my own pace (so it's a bit like learning online). However, it lacks the one-on-one advantage of having a live class or tutor. You miss that human element of it. Watching plenty of subbed anime will quickly get you familiar with short, common phrases.
Another problem that I've encountered teaching myself through books and apps is that most of them are for travelling, not really for someone that is honestly trying to learn to speak a language for the sake of speaking the language.
Personally, I would recommend trying a free online course, buying plenty of books/downloading several apps on the subject, and maybe trying it out in a classroom to see what suits you best.
However, trying it out in the classroom would also have the disadvantage of being incredibly stressful because you are getting a grade for it, and you aren't necessarily learning at your own pace.