Hi, as a Gold 4 player that is looking to climb ranked while supporting, I would like to know which supports are the most entertaining to play while being strong. I already own and play Taric and Leona and I really enjoy them. So if anyone has any suggestions, I would be very thankful!
Ps. I also own nautilus, annie, and velkoz.
My favorite is Nami. You might consider Thesh too.
As a support main myself I'd highly suggest Alistar. I haven't found another support that is as gratifying as Alistar is when you land an excellent w q combo.
Top supports like Thresh and Janna are always strong.
Blitz is of course, that annoying little champion. Brand is a neat support pick, albeit odd. Then you have your Zyra, Lulu, Morgana and Braum support.
I'd recommend 3 support champs. Veigar is an off meta support, but his event horizon if you are a good aim has major lane control. Maokai is a little bit more typical, he has great utility and vision ability with his saplings. he has 2 slows, 1 root, and an aoe damage reduction ult as well as good synergy with face of the mountain from his passive. Thresh is a top tier support, although the trouble with thresh is that the items that work really well on him have active abilities so you better learn your numbers.
I'm gonna follow suit with everyone else and name Thresh. You said you primarily use Taric and Leona as your main supports. Both of them are tanky style supports and Thresh is tanky himself so he may suit your play style. He primarily works as a kill/poke style support (Just like Leona). He does take some getting used to though and he requires your teammates to know what the lantern actually does.
Janna is another great choice and cheap too. She is the Queen of peeling and can cover up an ally's poor positioning granted they don't frequently misposition themselves before all of your stuff comes off cooldown. Janna is a poke/sustain champion.
Tahm Kench is the last one I'll state. Tahm Kench thwarts assassins quite well by swallowing up whoever they are beating up on and getting them to safety quickly. He is great at preventing idiot teammates from dying atleast 2 times per game. His playstyle is sustain/kill (just like Taric).
You might be okay on tanks with those two. If you want a little more specificity for tanks, 
is the best at keeping a team safe from heavy skillshots, if your reactions are good.
You'll definitely want to pick up some poke/shield champs. 
are all good choices, though I would rank their viability in that order from best to worst.
is a great one to have already; I don't think anyone does all-in better than her as a support.
If you want to try some very specific champions, 
is the only healer of her caliber. 
is just the strangest, but if you can eke him out, then he can be amazing.
has such a good kit, and is a safe pick if it looks like you'll be going against a kill-lane. Poke, Shield, soft CC, hard CC, pseudo-heal, reveal, speed-boost, and an 80% slow?
Yes plz.
is a solid pick too, but she's easily countered with a kill lane (her sustain is mana-hungry and she's squishy with no real mobility). Though if you can get into her, managing auras w/ Power-Chord shenanigans can keep you quite engaged.
Wow thanks for all the suggestions (just got off a flight and was greeted with many ideas, was refreshing). Looks like I have to look into thresh janna and nami which seems to be the consensus. Last time I tried thresh he felt wonky with his flay being so hard to use tho...
I like playing Nami, due to her Crowd Control and W. W is good for ANY situation. Your ADC low on Health and the Enemy is chasing them? W on the Ally to heal them, and well as get some free damage on the Enemy. In an all-in Team Fight? Throw a W on the Ally closest to the Enemies, and watch that puppy go. You can use your E to empower either your ADC or APC in a Team Fight, dealing so much more Damage. If your Ally is chasing a low-healthed Enemy, throw an E on them and, upon hit, the Enemy is slowed. Follow a Q up with an ULT on the ADC of the Team Fight, and there's practically a guaranteed kill if your team focuses on them. Q can be a bit hard to hit, but it can be such a game-changer in a Team Fight if used correctly.
I think personally Sona is an AMAZING support. Her Q is a great poke because it homes in on champs and does a substantial amount of damage when full upgrade. Her W is great for keeping your ADC alive especially when they are under attack or when going after more than one enemy at the same time. Her E can turn a chase into a kill very quickly for any of your ally champs. And her power chords also make a huge difference. Her Ult also does great damage and has a amusing stun with a fairly short cool down. Shes really fun to play i suggest her and build her full AP so her W and Q do great healing and Damage
