The GBA games have amazing atmosphere, and for HoD and AoS at least, pretty good graphics. (HoD actually focused on the graphics, thus leaving the music to suffer a bit)
the gba games really feel like legit sequels and inheritors to the metroidvania design, while the DS games really feel like cheaper cash ins just riding on the metroidvania bandwagon. The generic anime art stylke used for PoR and DoS doesnt help either, and neither does the fact that both have not only a terrible art style, but equally terrible 'sequel' stories. their atmosphere is also just really nonexistant. I would really recommend Dawn for Julius mode, and ONLY for Julius mode. Just ignore that the Soma main game exists and play the CV3 homage story. Which, actually has a story, unlike aria. Julius mode here takes place after Soma's bad ending.
TLDR, play them all, they all have their worth, but if you have to pick, go for the GBA ones first. At least Aria, because Dawn is a direct sequel to it, so you should really play it first.