Cards not yet mentioned:
Wordmail is a beating and a half if you support that kind of deck.
Empyrial Armor can provide similar results too. They can definitely feel removal-checky.
Archangel of Thune is a high powered top end by itself that benefits from incidental lifegain or a total build around in a pridemate deck, not to mention the combo with zuran orb.
Planeswalker-wise,
Ajani Goldmane,
Elspeth, Knight-Errant, and
Gideon Jura are all best in class at what they do.
Elspeth, Sun's Champion finishes like no one's business. These are all pure power level choices, but if you want to brute force the issue, they all work.
Citadel Siege is a powerful value accumulation engine that doubles as over costed removal if that's what you need.
The 3 mana double strikers all make me want to play a white deck. This includes
Prophetic Flamespeaker who, in spite of the fact he clearly is not only red, but double red, makes me want to play white.
Shelter is my favorite cube card, period, but I doubt many other people would happily first pick it. If you play lots of wrath style removal it certainly loses some of its luster.