I've done both SDM and Yakumo Clan lineups and both can work fine, at least up until Plus Disk postgame. Chen kind of suffers from lowish ATK and poor defense piercing, whereas Patchouli has a lot of MAG and Princess Undine has decent defense piercing. Chen is definitely better from Plus Disk onwards, but she's nigh useless against the fights that most new players will struggle with[Tenshi, Mirror, Magatama]. Patchouli, in contrast, works pretty well for two out of three of those fights and her synergy team does well against the other one. Yukari is great, sure, but you also get her way after you get the rest of the SDM team, after the most difficult fights are over.