All of the answers are good. This is just by way of a heads-up, to emphasize the need for context.
What gave everyone difficulties is the some which you introduced into the sentence. Some are least ADJECTIVE does not work well in English. Some is an indefinite adjective or adverb: it does not identify specific individuals. But least and, usually, most are ordinarily only applied to definite entities, the specific individuals of a group who lie at one or the other extreme of the scale. (This is why in most cases least and the least are interchangeable.) Your source did not employ some but which—a definite pronoun or determiner.
There are exceptions. If ADJECTIVE and its complements in effect ‘partition’ the group modified by ADJECTIVE, it may be appropriate to use some to designate one or another part. For instance, this would work:
Some individuals are least reluctant to break into the discussion, while others are least reluctant to initiate a new discussion.
And most, unlike least, can also be employed as a non-superlative adverb meaning essentially very; when this is the case there is no obstacle to using some:
Some were present only to hear the panelists' views and were most reluctant to break into the discussion.
This use is mostly literary; you are unlikely to hear it in conversation.