First, finish maxing out any 5s you have at 4/X. Then max your 4s at 4/X. Don’t worry about ascending anyone before finishing a hero on the home stretch. After every hero at that stage is maxed, level based on what you have materials for. Also, remember that E&P is a long term game. It’s a marathon, not a sprint. There’s no sense in trying to rush any hero until you have the materials for it’s ascension.
I’m sorry you maxed out Obakan. He is one of the worst dark 5* heroes. Sartana would have been a MUCH better choice. But if you had him first, he’s still better than no 5* dark hero.
For Red heroes, Marjana is a much better hero to max than Khagan. She’s a very strong sniper, while Khagan is really only good as a tank in your raid team. Obviously, finish up Grazul first, she is a really good healer.
You have a really nice set of Yellow heroes. Leo is a better choice to max first instead of Ranvir. You have Miki already, so Ranvir is only really good for fighting the rare blue titans you can’t use Miki against.
As to your blue heroes: For titans, Miki is your very best hero. He’s worth using against EVERY titan except rare blues (because rare blue titans reflect all blue tile and special damage and effects). His attack buff is the overall strongest in the game. While Ranvir can get you higher damage on some hits, his miss chance can hurt. Attacks buffed by Miki don’t miss. Also, Miki’s buff stacks with that of Boldtusk, or that of Bear and Dragon banners. It does not stack with Ranvir’s buff (or those of WuKong or Tarlak if you get them). As to picking between Thorne and Rumplestilstkin, Go with Rumple. Thorne is very similar to Richard, so he brings nothing new to your roster. Thorne is also considered one of the worst 5* blues. For 4*s, Grimm is great. His defense debuff will let you wreck enemies. Of all the heroes with that special, he has the strongest attack but the weakest defense. Use him offensively, because in a defensive roll he can be killed fairly easily.
As to Greens, Kingston is a REALLY good hero. Better than Lianna in most circumstances. But Lianna is the best original Green 5*, and is the highest damage fast single target sniper in the game. You won’t mess up by maxing either one. Of your 4*s, Hansel is incredible. His special can truly ruin an enemy’s day. I love using his special against a very fast mana enemy, and then charge up the enemy’s mana every turn, letting it kill itself.