Dragons are enormously frustrating because there's no substitution. With manyus, you can use more lvl 20s to get to the same place you'd get with a level 100. Sure it'll cost you more money but that's the tradeoff. With dragons, I just grit my teeth and sell off the excess lvl 5s and 20s (sure I could evolve 2*/3*/4*, but that'd take manyus I don't have to get them to the max level as it is).