What is Antony's true opinion of Brutus?

Antony seems to be expressing his true opinion of Brutus at the very end of the play, when he and Octavius are standing over Brutus's body on the battlefield at Philippi.

This was the noblest Roman of them all.
All the conspirators, save only he,
Did that they did in envy of great Caesar;
He only, in a general honest thought
And common good to all, made one of them.
His life was gentle, and the elements
So mix'd in him that Nature might stand up
And say to all the world, “This was a man!”

Antony, however, was a realist like Cassius. He could recognize that Brutus was a good man and yet not really respect him because he was gullible and easy to manipulate. Antony recognized that Brutus was an idealist. Both Antony and Cassius knew that this is not an ideal world. Brutus would have known better if he had not buried himself in books and meditation. Brutus might be compared to Hamlet, who was also an idealist and who came up against vulgar reality when he returned to Elsinore after his father was murdered by his uncle. Early in the play, when Cassius feels he has succeeded in persuading Brutus to join in the conspiracy to assassinate Julius Caesar, Cassius says to himself in a monologue:

Well, Brutus, thou art noble; yet, I see
Thy honorable metal may be wrought
From that it is disposed; therefore it is meet
That noble minds keep ever with their likes;
For who so firm that cannot be seduced?
Caesar doth bear me hard, but he loves Brutus.
If I were Brutus now and he were Cassius,
He should not humor me.         I.2

Both Antony and Cassius recognize that Brutus is noble, i.e., honest, altruistic, patriotic, kind, considerate. But both appear to believe that there is something better than being noble-minded. Both Antony and Cassius are shrewd and practical men. They are not noble. Both of them manipulate Brutus by appealing to his exalted self-image as a noble Roman with noble ancestors. Brutus might be described as an example of the saying: "Nice guys finish last." Shakespeare shows in the ruthless behavior of Antony and Octavius after their victory over Brutus and Cassius that it is usually the selfish, hard-nosed realists who come out on top.