Who Would You Pick & Why ?

I have been playing League for some while now [My first login-screen was Vel'koz & then I remember Sion] Haven't really touched Ranked, but the first time I played I got placed in Silver 5 and then my PC broke so I had to use a more laggy-unstable PC so I didn't touch Ranked ever again.

I have a better computer now, it's really stable for the most part, and I'm building up a Ranked Champion Pool. Been spamming Fizz in Normals to get the better hang of him, and I analyzed my playstyle. I can go Top, Mid, and Jungle (but people flame me a lot when I jungle since I don't gank bot.)

I am best at Champions who are mobile, ability-reliant, and bursty, therefore I have concluded I'm an Assassin Main.

I've been thinking, and I don't know if I should purchase Talon [pretty underrated and less likely to be banned, but very strong and has one the quickest burst in the game.] or Renekton [he's not an assassin but his abilities in my opinion still suit my style, and I love being a tank with damage.]

I plan on climbing starting after this purchase so which one seems more viable?

Who do I pick then? And why?