I'm at a loss of which champion to buy to further develop a well-rounded skill set. I have a bit of experience playing mid and top with Kat/Azir/Veigar, and Morde/Kha respectively. I'm afraid I'm spending too much time with more independant champs that snowball too easily, when I should be spending more time with team-focused champs. I'm currently thinking Lee-sin as the next champ in the lineup? I'de appreciate any input. Thanks!
I honestly think their are way better "team focused champ" than Lee Sin
you MIGHT save someone with safe guard
you MIGHT lol who am I kidding, you ult someone away and you will definitely save some one lol
his only contributions to a team fight is ulting correctly
and most tanks have CC that can do what he does with significantly less effort
Lee either goes snowball or control. He's a great champion, obviously, and if you're interested in him, go for it. That said, there are better team oriented champions.
If you want to jungle, I'd recommend Nautilus (massive utility, very much dependent on his team, also stronger than most think - he's my plat 5 jungle main).
You could also try support with Thresh/Morg, who are also very team dependent and strong.
Orianna is always a good choice for AP mid and her power is very much tied up in teamplay and less so in her individual ability to deal damage and carry.
Top is kind of an island, but you could try Shen/TF/Panth to more easily impact other lanes with ult mobility.
GL!
If you play top and mid consider 
