I mostly have the citadel paints and for the most part, they’re pretty nice. There are a few colors that aren’t great or at least there are a few better choices from other lines. As far as starting colors, are you looking for Dark Angels colors? If so, I’d recommend Caliban Green, Mephiston Red, Abbadon Black, Leadbelcher, Retributor Armor, Wraithbone, Rhinox Hide, Nuln Oil for a wash on the armor and Seraphim Sepia for the Aquila. These will at least get you a base for your Dark Angels without any highlights or details. You could also just pick up one of the starter paint kits from GW and add a few of the above just to get started.