That depends on where you are in the song and where you are going. It also depends on what the bass is doing. If you want to stick to the scale degree chords, it's easy to find chords that fit those notes. Here they are for the key of C:
C-E-G, D-F-A, E-G-B, F-A-C, G-B-D, A-C-E, B-D-F
Melody note D: D-F-A, G-B-D, B-D-F
Melody note E: C-E-G, E-G-B, A-C-E
Melody note B: E-G-B, G-B-D, B-D-F
If you want other chords, then refer to what I said first in this post. So, how about an example of a song or progression so that we can better assist you?