It depends on the week. in elo certain cards cannot be used. there are 2 types of banning:temp and perm. after every week people vote which cards they want banned. cards which get more bans than keeps with over 5% of votes are banned for the next week. perm bans can never be used. it all depends on the cards that are temp banned
e.g. normally either saki or marina or another all star is temp banned but this week none were. they were very powerful that week and many people used it. what people are using (clan wise in general) is called the meta. it is normally a good idea to go with what clan(s) you are comfortable with or with or against the meta (not as good to use clans that are weaker to the clans that many people use/are stronger that week)
if you are weak with all stars for example then don't use them
La junta may be "the best" that week but i will use a deck I'm comfortable with. i like to have attack manipulation or SOB as a bonus but that is my preference. i can play without them, don't get me wrong but they would be my choice.
i recently tried using a clan without those things (skeelz) and did well with them
also at your level you won't do that well in elo to begin with. u need experience. when u play more u may become awesome but it elo is highly skill based