Yeah, Riri is really mean after her rework. She's one of those fourstars that fivestar players choose to use when boosted... There aren't that many of them. Definitely a good investment.
Are you considering Hulkbuster as the "better option" to Riri? Riri's red has a higher damage output per AP, and her blue is a much better feeder Power.
Captain Falcon is one of those "use only when necessary" fourstars unfortunately, so you shouldn't feel any rush to level him.