どちら or どちらの方 in a question

Question

What is the nuance between どちら or どちらの方 when used in a comparative question ?

For example, what is the nuances between these two questions :

• おみやげはゲームとマンガとどちらの方がいいでしょうか。
• おみやげはゲームとマンガとどちらがいいでしょうか。

Answer 1

Consider a pattern "XとY、{どちら/どちらのほう}がZ". どちら will be preferred in following cases:

• Z is unique: (Looking at a photo showing two women) 右と左、どちらがあなたの奥さんですか？ Which is your wife, right or left?
• Z lists alternatives with どちらがZ1でどちらがZ2: (Speaking of an argument between two people A and B) AとB、どちらが正しくてどちらが間違っているというわけではない. It is not that A is right and B is wrong or vice versa.

Slightly more generally, if what Z describes has an exclusive nature (like uniqueness), then どちら sounds more natural; Otherwise if what Z describes has a nature of spectrum, どちらのほう sounds more natural.

[Edit] Regarding your particular examples,

• ゲームとマンガどちらの方が: The speaker assumes both can be ok, and asking which is better. As a matter of common sense, this is the more likely case and sounds more natural (いい is understood as expressing a spectrum).
• ゲームとマンガどちらが: The speaker assumes one is fine but the other is not, and asking which the present must be. (いい is understood as opposed to だめ=bad)

In other words, どちら imposes a choice; どちらのほう should be the norm if the question is a comparison.

That said, practically you can use どちら/どちらのほう interchangeably. In my examples above, using どちらのほう should be acceptable. And in your example, using どちらが will not change the meaning. (the responder will not really reply in the sense of which the present must be).

On preceding particles の/と/Zero

Short answer is: there are cases の is required for grammatical reasons; と is used mostly for a style; As long as the sentence is grammatical, の/と/Zero does not give any difference in meaning.

Use of の

• 二人のどちらがやったんですか？ Which of the two did it?

の is required so that 二人 modifies どちら. 二人と/二人 would be ungrammatical in this sentence.

One artificial example that makes preceding の (almost) ungrammatical when nominalized verbs are compared:

• 歌うのと踊るの(と)どちらが好きですか？ Which do you like better, singing or dancing?
• *歌うのと踊るののどちらが好きですか？

The latter might be acceptable to some ears. At least this is unlikely to be a written form.

Use of the second と

As for と, which seems to be categorized as a 並列助詞, sometimes it is preferred to use AとBと rather than AとB for clearly indicating what are put in parallel. As such it does not give any difference of meaning. But the second と is more for writing, and usually omitted in speech.

With the same reason as above (avoiding a consecutive appearance of the same character), one may come up with an example where the second と is unlikely to be used by considering a noun ending in と.

FYI 'preferred' above: I remember the use of the second と should be preferred claimed in a book written by a journalist.

Answer 2

I don't see much difference in the nuances of those two sentences. However, the latter sounds more natural than the former. I feel like 「どちらが」 is strongly bound to 「いいでしょうか」 so that there's no room for 「の方」.

「の方」 could be used more naturally in situations you choose one out of two. For example:

「ゲームとマンガ、おみやげはどっちがいい?」

「あー、ゲームの方がいいかなぁ」

Plus, it would be perfect if you correct here:

おみやげはゲームとマンガのどちらがいいでしょうか。