Art.

What's your favorite,most beautiful, most colorful,etc... That you can think of?

I really like foil artifacts in general. They look crisp and at the right angle they're just a neat shade of blue.

I think that tower drake from rtr has the most badass art.

Birds of paradise from core sets and Xenagod and nylea god

Unhinged island

Straight up Enter the Infinite

Donate, Priests of Norn, or Mojyin Of Life's Web

Too many to name:
Original  Balance
 Natural Selection
Storm Seeker

Straight up Enter the Infinite

second this allllll day long.

Pennon Blade in foil.

Baneslayer angel foil
Original progenitus

Foil Omniscience

 Wurmcoil Engine, such a nasty picture. For beauty,  Angel of Serenity.

sorin markov, vampire nocturnus, promo sun Titan

Silent Simulacran or however you spell it from the core set, or The full art Fitemane Avenger.