I've played several Mario games, my favorite of his being Super Mario World. But I choose Ratchet & Clank because it's a series that I hold really close to my heart. While Super Mario Galaxy has been a massive disappointment for me, Tools of Destruction and A Crack in Time have been brilliant entries with an engaging story without the usual predictable characters or outcomes. Even the 2016 remake was quite solid.
It's a series I've always been excited for whenever I see a new entry, with really likable characters with appreciative personalities.