Might be controversial with the other options, but based on only having R4s I would imagine you are in act 5. Gwenpool can be heavily utilized there with her AAR and her Plot Armor. She works perfectly at r4 for a progressing player and she is so fun to play.
If you run "suicides" masteries Omega and Namor are maybe among top champs (personally, I don't use suicides, but I find Namor useful for war and less in other contents). If you don't run suicides, Gwenpool is great for a lot of contents. Otherwise, I'd go with (awakened) Void, who is one of the best champs overall according to most players.
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If you don't run suicides, Gwenpool is great for a lot of contents. Otherwise, I'd go with (awakened) Void, who is one of the best champs overall according to most players.