I don't own very many, so:

1) God of War: Chains of Olympus
2) Syphon Filter: Dark Mirror
3) Ratchet and Clank: Size Matters

The other two, "Untold Legends: Brotherhood of the Blade" and "Spider-Man 2" suck, so I won't list them.

1. Hot Shots Golf: Open Tee 2
2. DJ MAX 1/2/F
3. DJ MAX Clazziquai/BS
4. Taiko no Tatsujin 1/2
5. Alex Dark's "Candy For Wolrd x5,2"

in no order what so ever..

Monster Hunter Portable 2nd G
Final Fantasy Tactics: Lions War
Jeanne D'Arc
Final Fantasy VII: Crisis Core
Phantasy Star Portable

Special mention to the Everybody's Golf series.. played it for hours with my gf.

Disgaea
Patapon
Tekken DR
Crisis Core
Dissidia

EDIT: Responding twice in the same thread without knowing it = very bad. =)

God of war







Monster Hunter 2



Fifa street 2
R&C Size matter
Loco Roco

1. God of War: Chains of Olympus
2. Ace Combat X: Skies of Deception
3. Resistance: Retribution
4. Ratchet & Clank: Size Matters
5. Killzone: Liberation

Top 5:
Locco Rocco
Crush
Exit
Echochrome
Sid Meier's Pirates

Honorable mentions
Def Jam Fight for New York: The Takeover
Burnout Legends
Virtua Tennis: World Tour
Ultimate Ghost's 'n Goblins

1. Final Fantasy VII : Crisis Core
2. God of War : Chains of Olympus
3. Metal Gear Solid : Portable Ops
4. Ratchet & Clank : Size Matters
5. Syphon Filter : Dark Mirror

1. Final Fantasy VII: Crisis Core
2. Star Ocean Second Evolution
3. Star Ocean First Departure
4. Patapon
5. ...No game to fill this spot. Sorry.