I don't think it is a matter of power. Any one class could be more powerful than the other, but it is the idea that you get when you play it. A rogue could easily overpower any wizard, or warrior, if played properly. Then again, it is just a matter of preference.
But my all time favorite, would have to be a Bard. They make excellent, warriors, and a secondary mage. Especially if one picks the right spells. Nothing more devastating than a Bard who not only enhances the party, but cripples the enemy as well. To top it all off, is the thievery that enhances them.
My favorite character of all time, was a Bard named Tynian Nalgone, who sung parodies of things he heard or done. One of my favorite spells, was Tasha's Uncontrollable Hideous Laughter, talk about a hilarious time, when everyone at the table couldn't stop laughing.
"Oh, the orcs fall to the ground in an uncontrollable fit of laughter. Your players are parylized by the spectacle." So says the DM.