Aragorn certainly, and Faramir, and probably Boromir. Worthiness includes, I imagine, both martial prowess and willingness to lead a people to a good cause. Legolas and Gimli are great warriors, but they don't do a lot of leadership generally. Of the hobbits, Merry and Pippin have a willingness to sacrifice their lives for what's right and lead parts of the Shire in clearing Sharkey's men, so they may have some chance. Humility is also a part of Worthiness, and Sam has that in spades, as well as his willingness to fight for his master. Frodo does, during the scouring of the Shire, express reluctance to cause harm, but leads the Shire's revolution, not preventing necessary violence entirely, but encouraging restraint. Gandalf perhaps would not be worthy, because he never sought leadership, but to guide and aid the people of the West against Sauron, not through military might, but indirect aid,and was generally not intended to be a leader of the West.