Ascend or release?

Which dragon rarity are best to ascend? Is it worth spending the runes to ascend these and get amber or should I release them for runes and fish

Also does the level of the dragon when you ascend them make a difference on how much amber you get?

Which dragon rarity are best to ascend? Is it worth spending the runes to ascend these and get amber or should I release them for runes and fish

Also does the level of the dragon when you ascend them make a difference on how much amber you get?