Depressed is the strongest element by far on release of the game thanks to the global exclusive character 
Yomi Yomi .
She heals, buffs, debuffs the enemy and has great damage herself. A really strong unit everyone should pull for while her banner is up.
xXionx xXionx is our main damage dealer for this composition. 
Kidian Kidian can rival her damage depending oh the cards you get, but since she’s a frontline DPS, she can easily die for being squishy early on.
Kommy Kommy is our main tank for now. A good option since she can sustain herself with both skills and has good HP with her passive.
Hilde Hilde is the main healer for this composition.
Last spot is up to what you prefer honestly. 
Posher Posher or 
Rim Rim are the only real options in my opinion.
Posher Posher acts as healer but she’s pretty bad. Her utility with the potatoes is pretty good on both PVE and PVP.
Rim Rim can be used as a secondary tank thanks to her skills and even in KR that’s usually her main usage rather than being a pure DPS character.
At this time there is not a proper full composition for Vivacious Apostles.
Ui Ui will act as a healer, utility and sub DPS unit. Fantastic character that will be used on these teams for a long time.
Momo Momo is our main damage dealer and this Naruto girl can dish out a lot of damage with her clones. Safe investment for the future.
Butter Butter arrived recently and she is both a damage dealer and buffer for this team. Her passive increases every Vivacious ally damage, making her a staple for this tower and any elemental content where you bring Vivacious units.
Rudd Rudd is the only option to tank and she is a lot better than her KR version thanks to her passive. While still not strong enough for the future, should be enough until we get other banners.
The rest of the units here are fillers. None of them are particularly good, so you can go based on what designs you like more.
At this time there is not a proper full composition for Madness Apostles. In fact, they’re the weakest personality at launch.
Chloe Chloe is a fantastic tank with good self sustain that will be used for a long time on Madness personality based teams.
Diana Diana is the main healer here and she is quite future proof since she increases damage for all Madness allies, making her a staple pick for any Composed content.
Shaydi Shaydi is great for raids thanks to her Silence and at the moment, the strongest damage dealer for this team. Just like Kidian Kidian , be careful she does not die since she’s quite squishy.
Belita Belita and 
Alice Alice are both damage dealers that are underwhelming compared to the other personalities. Worth investing until we get other Mad units if this is your main personality.
Vivi Vivi is the strongest tank in the game and she will always be (until 
Vela Vela comes out), a good pick for Yggdrasil, campaign and raids.
Gabia Gabia is the main support for now on this team. She has great synergy with Vivi Vivi , but is not a proper healer. Long term she might be replaced with better options, but safe investment until then.
Haley Haley is one of the main damage dealers with great utility thanks to her stuns. Her passive is still something we’re testing, maybe there’s a team based on DoT that can be really strong, for now we’re just coping.
Erpin Erpin is the second DPS and also a buffer for all Innocence allies. She will be a staple on Yggdrasil and raids, making her a safe investment for the future.
Last two spots are fillers for now, so just pick based on design until more Apostles arrive.
Aya Aya is a great damage dealer that only got better on the global server thanks to her passive. She increases damage for all Composed allies, making her a safe pick long term for Yggdrasil and raids.
Amelia Amelia is our second DPS with a lot of utility thanks to her Senior and Passive skills. Great waifu too, go buy her skin.
Picora Picora is the main healer with a team wide passive to reduce incoming crit for everyone, which is good at high deficit to avoid getting one-shot.
Until other options arrive, 
Velvet Velvet is the main tank on this composition, she is a lot better than the Korean server but I’m not sure it’s at the level where we can call her a safe investment.
Sylla Sylla and 
Jade Jade are the filler units for now, providing mostly damage. I would not heavily invest into either unless they are your waifus.