[Legolas]

Tom isn't really an option. It's stated that he was so apathetic and forgetful that he would undoubtedly lose the Ring and his focus to destroy it very easily.

'He would not have come,' said Gandalf.
'Could we not still send messages to him and obtain his help?' asked Erestor. 'It seems that he has a power even over the Ring.'
'No, I should not put it so,' said Gandalf. 'Say rather that the Ring has no power over him. He is his own master. But he cannot alter the Ring itself, nor break its power over others. And now he is withdrawn into a little land, within bounds that he has set, though none can see them, waiting perhaps for a change of days, and he will not step beyond them.'
'But within those bounds nothing seems to dismay him,' said Erestor. 'Would he not take the Ring and keep it there, for ever harmless?'
'No,' said Gandalf, 'not willingly. He might do so, if all the free folk of the world begged him, but he would not understand the need. And if he were given the Ring, he would soon forget it, or most likely throw it away. Such things have no hold on his mind. He would be a most unsafe guardian; and that alone is answer enough.'