Which new creatures or hybrids to shoot for? That will depend on what you have access to. You will be limited to ones you can get enough DNA for to level up and fuse. Let’s take a look at what you have…
Looking over your posted crew, I would say you are a casual player as your high-level creatures are created from rewards. You do not spend a lot of time hunting. Judging by your resources up top, you do not have a lot of time for going out and spinning drops to gather coins. It looks like you rarely, if ever, max out on spins daily. Is this an accurate assessment?
I am not saying this is a bad thing!!! But in coming up with suggestions for team improvement it is necessary to evaluate what a player has to put into the game compared to what they can get out. A player who has limited time to put into a team will be different than someone who has more available resources to them. People can suggest to look at the top teams and shoot for all those end-game creatures. But if you are never going to be able to dart any of the ingredients, those end-game creatures are never going to happen for you. At least not in any kind of a time frame.
Ok. Based on that this is my short term suggestion. With the current match making, you have several creatures that are too high level on your crew. That level 20 Sino and 18 Einia are going to match you with much stronger opponents. Since you have nothing besides them at their levels to battle with, I bet when you do not get either picked in your 4, the battle goes very badly. When they get picked, you have a much better chance of winning. Correct?
I would suggest replacing them with something of similar level to your others, level 15 to 17. Yes, you are going to go on a losing streak, but you might be too high in trophies for your other creatures to deal with. You are getting lopsided matches because you are relying on two creatures instead of your whole team. To get anywhere near to fun battles, your weakest creature has to be viable in Arena alongside your strongest.
It is going to take you a long time (months and months) to be able to put together the resources to build hybrids with. Drop down in trophies a bit and try to enjoy the next few months while you gather DNA to start on hybrids at higher levels. You are better off at a trophy level where you can win enough (without a lot of frustration!) to keep an incubator running. They will give you a lot of valuable DNA, a well as useless DNA too.
Then, just start darting everything you can. Accumulate DNA from whatever you have available then see what you are able to create with it. Do not start fusing anything right now, do a bit of waiting and collecting. Save all your coins for now, just accumulate all you can. And lastly… Do not use any boosts on what you have now. Stockpile them for higher grade creatures.