Great.
As above it could be "Great" or you can say Grand. It really depends on what phrase your going to use it in like "I'm doing great" or "I"m grand". There really aren't very many definitions for good that also start with the letter G.
great
Tremendous
terrific
Playful is mybe another word for great
Hamper
'Pseudo-', meaning 'false' or 'unreal'.
Nice.
bonus -a, -um (adj. meaning good) perhaps?
In some contexts the word exemplar would have that meaning.
well,great ,fine
Car is another word for truck that starts with a "c".
Tremendous and terrific are synonyms for wonderful. They begin with the letter t.