Which pants is/are your favourite?

pants unless preceded by "a pair" is regarded plural.

I wonder in such situations

1. I bought a few pants during sales. Which pants (are) your favourite? Go pick two.

2. I bought a few pants during sales. Which pants( is) your favourite? GO pick one.

If we use "are" it sounds "awkward to me" if we mean only one.

However,

When without a given context, shall we always consider the subjects as plural?

Which pants are your favourite?
Which pair of pants is your favourite? (common to use "pair" in such a question?)