Metal Gear Solid would be my favourite for being fresh, yet consistent. Every game is immaculate. Followed closely by Final Fantasy, although quality is inconsistent and not every game is original, the soundtracks and worlds are almost always amazing.

Hitman

Pikmin or Pokemon.

Pikmin has a ton of memories for me and it is also a really well made game. It takes RTS(?) to a different level.

Pokemon is just pure fun. It's a great "Nintendo Twist" on an RPG.

Mario (includes 2D / 3D / Kart / paper) , Metroid, Metal Gear, Resident Evil (until 4), Unreal Tournament, Half-Life, Smash Bros.

I'd say Mario is the most well-known video game character/franchise

That or Pokemon. Pokemon is widely known too.

Final Fantasy. Even though the last few games haven't been as good as the older ones, I can't think any VG Franchises that can beat the story, gameplay and soundtrack of the final fantasy series.

This is a tuff one but I will have to believe the Ratchet & Clank games are the best for me imo.

SANIC HEDGEHOG.
no, seriously.
Dont hate bro

A Final Fantasy fan for life! Followed closely by Metal Gear and Pokemon!