Yesterday, I grabbed some games which I own and which are/were in the final rounds of this megapoll. I still believe Illusion City has the nicest artwork. But I admit, that's also because of the back of the box and the size of the box itself. There's more artwork than the game-cover 
...Uhm, Aleste 2 is really great, but the box itself is rather small. Ok, you don't see that in this megapoll and maybe it's not what this megapoll is about, but then I might have had wrong perceptions. It's just. I like it big 
Microcabin boxes are so fantastically BIG And Aleste 2 is a bit of a let down, if you have the original in your hands, really .....Anyway, it's about game-cover artwork, I know. Then Aleste 2 should win hands down.
Latok, stop gibbering about nothing ^_^
And some final ASCII art 
F1 Spirit ---------+
|- Hydlide 3 ---------+
Hydlide 3 ---------+ |
|- Hydlide 3 ---------+
Seed of Dragon ----+ | |
|- Dragon Slayer 2----+ |
Dragon Slayer 2----+ |
|- Hydlide 3 ---------+
Freddy Hardest ----+ | |
|- SD-Snatcher -------+ | |
SD-Snatcher -------+ | | |
|- SD-Snatcher -------+ |
Metal Gear 2 ------+ | |
|- Teitoku Ketsudan --+ |
Teitoku Ketsudan --+ |
|- Hydlide 3
Penguin Adventure -+ |
|- Chichén Itza ------+ |
Chichén Itza ------+ | |
|- Illusion City -----+ |
Illusion City -----+ | | |
|- Illusion City -----+ | |
Dynamite Bowl -----+ | |
|- R-Type ------------+
Bastard -----------+ |
|- Bastard -----------+ |
Frantic -----------+ | |
|- R-Type ------------+
Blue Warrior ------+ |
|- R-Type ------------+
R-Type ------------+
Yie Ar Kung-Fu 2 --+
|- Genghis Khan ------+
Genghis Khan ------+ |
|- Undealine ---------+
Undealine ---------+ | |
|- Undealine ---------+ |
River Raid --------+ |
|- Xak Gazzel --------+
Metal Gear --------+ | |
|- Metal Gear --------+ | |
Seigimachu II -----+ | | |
|- Xak Gazzel --------+ |
Heroic Citadel ----+ | |
|- Xak Gazzel --------+ |
Xak Gazzel --------+ |
|- Aleste
Super Rambo Spec. -+ |
|- Aleste ------------+ |
Aleste ------------+ | |
|- Aleste ------------+ |
Hydlide -----------+ | | |
|- Hydlide -----------+ | |
Andorogynus -------+ | |
|- Aleste ------------+
Magical Kid WIZ ---+ |
|- Gradius 2 ---------+ |
Gradius 2 ---------+ | |
|- Gradius 2 ---------+
Contra ------------+ |
|- Contra ------------+
Sengokugunyuden ---+
Columns -----------+
|- YS 1 --------------+
YS 1 --------------+ |
|- Hydlide 2 ---------+
Xak II ------------+ | |
|- Hydlide 2 ---------+ |
Hydlide 2 ---------+ |
|- Hydlide 2 ---------+
Satan -------------+ | |
|- Satan -------------+ | |
Nemesis -----------+ | | |
|- Nemesis 3 ---------+ |
Nemesis 3 ---------+ | |
|- Nemesis 3 ---------+ |
Valis -------------+ |
|- Hydlide 2
Xak I -------------+ |
|- Xak I -------------+ |
Sorcerian ---------+ | |
|- Salamander --------+ |
Guardic -----------+ | | |
|- Salamander --------+ | |
Salamander --------+ | |
|- Salamander --------+
Vampire Killer ----+ |
|- Vampire Killer ----+ |
Maze of Galious ---+ | |
|- Princess Maker ----+
Fray --------------+ |
|- Princess Maker ----+
Princess Maker ----+
Game Over ---------+
|- Game Over ---------+
Ashguine 2 --------+ |
|- Deep Forest -------+
Deep Forest -------+ | |
|- Deep Forest -------+ |
Ark-A-Noah --------+ |
|- Deep Forest -------+
YS 3 --------------+ | |
|- YS 3 --------------+ | |
YS 2 --------------+ | | |
|- YS 3 --------------+ |
EYE ---------------+ | |
|- EYE ---------------+ |
Navitude ----------+ |
|- Aleste 2
Star Fighters -----+ |
|- King's Valley II --+ |
King's Valley II --+ | |
|- Haja Fuin ---------+ |
Haja Fuin ---------+ | | |
|- Haja Fuin ---------+ | |
Treasure of Usas --+ | |
|- Aleste 2 ----------+
Aleste 2 ----------+ |
|- Aleste 2 ----------+ |
King Kong 2 -------+ | |
|- Aleste 2 ----------+
Strategic Mars ----+ |
|- SNATCHER ----------+
SNATCHER ----------+