In this case, it should be wa. The difference between we and ga is rather complicated. The most basic idea is that wa is the topic you are talking about, something already mentioned in the conversation while ga introduces something new. Often it also helps to think that wa is the greater topic, while ga is a sub-topic of wa. For example, Watashi wa ashi ga hayai. About me: about my legs: fast. My legs are part of me. Also, it is generally expected that you are talking about yourself hence you are "the basic topic", while "your legs" are the new topic. Similarly "Watashi wa anime ga suki da" - In this case you are talking about yourself, how you life anime. You are the basic topic and anime is the sub-topic that you brought up just now. On the other hand, if you would say "Anime wa watashi ga suki desu" it would mean that the general topic is anime and in such a conversation you say that you too like anime. But this order is generally less common. There is also that ga puts more emphasize on the subject while wa puts more emphasise on the predicate. This can be best observed by questions. When you are asking WHO did something, you always use ga. Wa is generally preferred. When there is only one subject particle in a sentence (barring sentences where the subject is omitted such as "anime ga suki da" which would actually be "watashi wa anime ga suki da") then you usually use wa. Also grammar books say that there should only be one "wa" in a sentence and that ga should be used in a subordinate clause. This rule is in effect but it is not always followed by natives. Finally, ga is only used for the subject, wa can connect to any kind of topic, be it an adverb or (rarely) even an object. And as an afternote: ga also has different meanings besides the one that is opposed to wa.