I LOVE playing mid-lane. I usually pick Talon 
, Annie
, Fizz
(Fizz Is on Champ Rotation..... Should I get him?)
I was thinking on getting Yasuo
, knowing that he is hard to play
OR
Getting Katarina 
Any advice or tips on who I should get? Maybe someone I haven't thought?
Thx
as a mid laner...
play anything other than assassin.
assassins are not viable in 100% of team comps across all of your games. im not saying dont incorporate them in, but your team must centralize around it. its fine to counterpick with an assassin but if you're first pick you're going to regret it.
overall though id go with katarina, shes pretty freelo if you can play her well.
Yasuo. Hard to play. Lul.
Play Annie, Vlad, Swain, Malphite, and Pantheon if you don't want to become a one trick until at least plat. Those champions are way too hard for you. Before improving at important aspects (csing, team fighting, trading, rotating, warding) of the game you will need to learn your champion (Yasuo can take 500-1,000) because you will need to focus on things like how to play your lane and how to use your kit. You will also be a hindrance to your team because you won't be able to play champions like Yasuo anywhere near to his fullest extent. Very few high ranking players, if there are any at all, that are not one tricks have started out playing assassins from the first time they've played ranked. Normals are a lot different than ranked. If you continue playing the champions you do, you'll land in low silver/bronze and take an exponential amount of time to climb.
Assassins work better in solo queue but worse in designed team comps. The reason being is because solo queue has much less communication along with most people doesn't want to have to be the tank if the team needs one and most people in solo queue don't think about having to pick a champion for wave clear if their team doesn't have enough.
If I was you I would get someone completely different than the assassin/burst mages you play so far. Try out a different mid and see how you like it, at the very least it will help you understand different play styles for those champs when you face them later. Some champions to consider getting are 
If you really just want yasuo or katarina, get kat as her mechanics are far easier to learn than yasuo.
