The best are C, E and G, as they actually make up that chord. Depending where in the bar you sing other notes over it, others may or may not fit. Your ear will tell you better than a written explanation. The chords you show are not diatonic- they don't all come from the C key.
What chords sound good with what notes?
- Group 1 – G, C, D, and Em – (Key of G Major, All Open Chords)
- Group 2 – The C, F, G, and Am Group – (Key of C Major)
- Group 3 – The D, G, A, and Bm Group (Key of D Major)
- Group 4 – The Am, G, F Group (Key of A Minor)
- Group 5 – The A7, D9, E9 Group (The Blues In The Key of A)
How do you match chords to a melody?
Here is how it works. Start with the 1 chord and play it underneath your melody until it doesn't sound good anymore. When it stops sounding good, look at the note you are playing in your melody and try to find a chord that contains that note. Use the 1-4-5-6 chords as your first guesses.