New Life Spectrum all the way! As far as size of pellets it depends on how big your fish are. For my Coral Beauty Angel and Maroon Clown 1mm pellets are perfect.
So for 1mm pellets go with either "Marine" or "Thera Regular."
For 2mm pellets go with either "Medium Fish" or "Thera Medium"
For 3mm pellets go with either "Lg. Fish" or "Thera Lg." and so on.
Heres a link to NLS's website so you can see all different types of pellets they make.
NLS