At risk of sounding like a broken record, if you're on an iPad, jukebeat/jubeat plus and REFLEC BEAT plus should be in there. taiko no tatsujin plus and osu!stream also have permanent places on my iPad, alongside the already mentioned Groove Coaster. And I guess Cytus is worth a try, despite the massive judgement windows and off sync charts.
By the way, we're expecting a new KONAMI music pack for jukebeat to hit within hours, if they continue to stick to their every-other-Monday schedule. This will be the last one before reaching the copious pack updates (which jubeat plus is one pack away from finishing).