The music in Dynastic Hero sucks. The reskin in general looks very ugly to me, and the series is on much surer footing in its fantasy trappings than the generic anime bug world of DH. If you felt it brought down the action, then I'd say the music in Wonder Boy in Monster World is far more appropriate - and frankly a more memorable and likable OST.
Wonder Boy in Monster World is superior in a few ways - notably, the US version has its difficulty increased (though the game is still on the low end of the challenge spectrum), the writing is better, and obviously the character sprites are far more pleasant.
As for games to play, both Genesis titles are winners (this doesn't include Monster Lair). I know it's hard to think about playing Monster World after playing DH, but maybe you can emulate it to see if you like the changes. I would honestly feel bad if someone's only exposure to the series is the Hudson reskin hackjobs.
Monster World IV is a slight step down from WB in Monster World, but it's a very good game full of polish and personality. It has large dungeons to make up for its lack of exploration. it's not quite a worthwhile tradeoff to its predecessors open world, but it's quite nice - the dungeons themselves are very involving and contain some tricky puzzles and bosses.
World-style game is Dragon's Curse for TG-16, aka "Adventure Island" for PCE.
Since these games are very fresh in my mind I will have to disagree with Black Tiger.
While I haven't played the SMS version, Dragon's Curse/Adventure Island is full of good ideas that wouldn't be better realized until the Genesis/MD outings. While there is a novelty in having an open world, the way things are segmented is a little artificial, since you often need to be a certain form to enter into a new world. While it accentuates the "uses" of the animal forms, it devalues them because you will only ever be able to use them in their own small 5ish-screen area, and a little bit in their respective dungeons.
WB in Monster World is more natural in this regard, as it has a larger world and a more open hub for you to explore. Your access to new areas is determined by equipment that (importantly) you can swap in and out any time, with the exception of the Pygmy dungeon.
Dungeons in Dragon's Curse are mostly long horizontal stretches populated by enemies. They're short enough to not overstay their welcome but they get samey after a while. WB in MW's, while not as involved as Monster World IV, are a marked step up from its predecessor. Comparing the final dungeons alone can show the advances in level design. And the final boss of WB in MW isn't a cheating prick like the one in Dragon's Curse.
Dragon's Curse is a very good game and it was really fun to see an open-world game attempted so early in the series' lifespan, but I think successive games really improved on its formula. It's still worth at least one playthrough.
