It's up to you.
if you want to get fast money in order to get decent deck, sell him
and actually, there is no point on keeping him though..
+1 damage will never make you go anywhere if you don't have decent cards
wait for hugo if you want a decent leader (you will get it a level 15)
ask us if you confuse how to build a good and cheap deck, we are here to help
La junta is exensive for beginners..
what I recommend is:
all of them is good for budget player
if you still want to keep your la junta
maybe you can pick your second clans:
if you want to use hugo, uppers or montana is a good choice
I'm sorry, maybe it's kinda limiting your choice, but they have some cheap and good cards right now
I see that you cannot sell your cards on the market, if it is at all possible buy at least a few credits to unlock that ability. Then you will be able to get more value for your cards and build the deck you want.
As the others mentioned, pick one or two clans and buy good cards.
You might try looking at the public presets for ideas on inexpensive good decks.