I don't particularly like fussy box arts, so the ones that stand out to me are the more minimalist ones.  Squaresoft used to be very good at this:

Just an important theme of the game placed behind the title.  Always looked really great to me.

Other than that, there aren't a great deal of box arts I actually like that much.  Most I find much too busy.

thats just awesom!! im sad max payne 3 didnt do so good. i dont think we will ever get a max payne 4

that bioshock infinite is the back cover! dont cheat! we all know how bad the real box art is

that secret of mana box art is beautiful though

but everyone who isn't crazy will use it so it's like we have it at home^^

Ooh I like this topic. There are some really good ones out there, most of there best cover art are from niche games that everyone forgets about. I'll see what I can find in my library of games and I'll post them below:

NOTE: Right Click and choose "View Image" to see full size.

Panzer Dragoon (Japan Cover) - Sega Saturn

Monster World IV (Japan Cover) Genesis

ICO (Japan Cover) - PS2

GunLord - NeoGeo/Dreamcast

Alisia Dragoon - Sega Genesis

Snatcher - Sega CD

Star Fox (Japanese) - SNES

Doom - PC

If I think of more I'll post them later.

We have a winner!

Chrono Trigger
Terranigma
Illusion of Gaia
Soul Blazer
Secret of Mana
Final Fantasy VI

just to name a few.

you of all people im surprised didnt post the halo reach box art, its just VERY cool IMO and i thought probably the biggest halo fan on the site would think the same :-p