Hey gameboyAdv,

It really depends what kind of playstyle you like. Personally I think Nami has very high potential. You can play her passive, but situationally you can go more aggressive than Soraka due to her kit. She's got quite a similar playstyle to Soraka, as in her Q is a circle aswell (little bit smaller radius) but knocks up enemies, giving more aggression to her kit, her W heals quite alot too but also brings damage due to bounces, E is a speed/dmg buff for allies (or yourself), and her ult is the biggest difference maker, huge line aoe knock up, this makes you be able to play Nami alot more aggressive when needed or when you want to outplay.

Sona has a similar playstyle to Nami (R stun and W aoe heals are somewhat similar), but has more rotation potential (E), so if you're into healing and making rotations faster than enemies, this is your champ.

If you're more into rotation making (E) and playmaking (Q and R) tanks with sustain (W), I'd suggest Bard.

Janna's playstyle is more laid back, pretty passive playstyle (very similar to Soraka), alot of shielding (E), but also brings disruption (Q knock up, R aoe heal aswell as knock back enemies) and slows (W). The hardest thing about mastering Janna is probably using her ult, it sounds simple but small differences in plays can make a big difference. Sometimes you see Janna's flash behind enemies and ulting to knock them back into your team, I don't really recommend that because you're using quite alot of resources (both flash and ult for usually just one kill). You usually want to use your ult (during fights) to heal up as many teammates as possible to keep pressuring towers whilst enemies have to recall. Depending per situation, sometimes you want to ult and heal your allies and knock back enemies as much as possible, but sometimes you want them not to be knocked back too much so your teammates are still in their range and can kill them. So situationally you want to know your exact ult aoe range so you can knock back enemies just an inch for that disruption whilst keeping them in range for your allies to kill them.

I would say Karma's playstyle looks alot like Sona's playstyle but is just a little bit different.

Morgana is a very unpopular support pick, but due to her low popularity you'll more likely get good Q bindings because it'll be more disrespected unlike Thresh and his hooks, her kit isn't so great I would say, black shield requires you to respond very fast to CC and her R is very hard to manage as you usually want to get alot of enemies stunned but due to her squishyness you're likely to die fast, meaning 1 or 2 is pretty much the max enemies you can deal with.

Lux isn't really a support but hey if you really feel like playing something hype and carrying by dealing loads of damage and hitting alot of ults you can pick her, you'll probably want to build alot of dmg items because 3 of her 4 skills are dmg abilities.

You probably want to try out Nami/Janna/Sona. Fyi, if you need tips on builds or what to max first on the champion you're gonna play feel free to pm me :)

Hope that helps you picking up some more supports :3