When it comes to どちら (dochira) and どっち (docchi), I would prefer どっち in more casual conversation, but どちら sounds better when talking about more than one thing. I mainly use dochira in a question about which cities or even languages, but I like using docchi when asking about, say, when the subject is already stated. Dochira is also good when asking what is good and for reason, but docchi is not so much. It's a little hard for me to describe, but here is the best I can describe: Docchi: casual/formal. Good for many things except asking the following: 1: Which is better, ______or_____? 2: Which is more_______? (few cases are acceptable.) 3: Which is more _______, ______or _____? Dochira: kind of equal in social meaning to docchi, but not quite. Goes for all of the above cases, including: 1: Out of _______, _______, and _______, which is more _______? (Only one for this) It was hard for me to describe its function, but I hope this helps.

In daily conversation: 1. I'd say どっちですか[docchi desu ka]? (or どちらですか[dochira desu ka]?, which would sound more formal.) 2. I' d say わたしのはどっちですか[watashi no wa docchi desu ka]? (わたしのはどちらですか[watashi no wa dochira desu ka]? would sound more formal). どっちがわたしのですか[docchi ga watashi no desu ka]? (or どちらがわたしのですか[dochira ga watashi no desu ka]?, which sounds more formal) would also make sense, though. 3. Never would I say どっちがもっといいですか[docchi ga motto ii desu ka]? nor どちらがもっといいですか[dochira ga motto ii desu ka]?. I'd say どっちがいいですか[docchi ga ii desu ka]? (or どちらがいいですか[dochira ga ii desu ka]?) or どっちのほうがいいですか[docchi no hou ga ii desu ka]? (or どちらのほうがいいですか[dochira no hou ga ii desu ka]?).

1. Which one? ------->どちら? or どっち? 2. Which one is mine? どちら は watashi no desu ka? ----->どちら　「が」　わたしの　ですか？ 疑問詞（ぎもんし）　の後（あと）は、「は」ではなくて「が」になります。 3. Which one is better? どちら は motto ii desu ka? ----->どちら　「が」　もっと　いいですか？　or どちら　の　ほう　が　いいですか？ がんばってくださいね！

It's for a bilingual class bookmark. This is why translation is so difficult... ^_^

Why don't you use どっち, which sounds more casual and is more used in casual conversation