I have a maxed out Sabina now.
Next could be Proteus, Rigard or Sartana.
Sartana is the only 5 star Hero I have for now but I think Proteus would be a better choice. Rigard just acquired 2 days ago but else I would have preferred him over Sabina.
What are your thoughts? Go for the 5 star or pick one (or two) 4 stars first?
Welcome to the E&P discussions
@Voske 
Proteus
Rigard
Sartana
is the right order.
Proteus is the epic game changer and will make you win against all bosses with a few mana potions. Since you already have Sabsy, Rigard can wait for Proto.
Rigard is the best epic healer and the only epic cleanser and therefore a superb supporter in wars and raids.
Sartana just hits hard. She’s more of an end game vanilla and you’ll be able to compete with and without her. Also legendary heroes need so much more resources to get leveled that you should wait to focus on her, until you’ll have at least about 10 maxed epics.
I one hundred percent agree with @Olmor. Proteus is definitely a game changer , and since you have Sabina already I would follow the order suggested. You will not be disappointed 
another vote for Proteus. he was my second 4*, and changed the game for me - Raids, Wars, quests and the world map all became so much easier.
Since you have a healer already, I’d switch Sartana and Rigard on that list. But ONLY if you have the mats to level Sartana. Just my preference… probably since I made it more than a year before I shared my first Rigard. While I was excited, he’s still languishing in my unleveled branch 
For leveling Sartana, you will need 6 tabards and 8 trap tools. Just FYI as you’re making your decision.
I love Rigard and plan to ascend a second one BUT you already have Sabina as a healer (although I don’t like her very much, too squishy).
So, first choice would be Proteus (love him too and extremely useful in every situation). I would also put some emblems on him to make him sturdier.
If you do also AW I would go with Rigard, another healer is always useful. Then Sartana… but it wouldn’t be wrong to ascend her before Rigard, she’s a very good 5s and hits hard
Thanks all!
I’ll go for Proteus as first choice and when he’s done I make a decision who’s next.
You’ll see how much easier events will become with him, especially last levels: when three 5s can’t load their specials, it’s just a matter of time for them to fall down
The answer is a easy one. Proteous is 1st. Because you have a dark (purple) healer maxed and if you have ALL it takes to get sartana to 4th then she would be my next choice for sure. Also sartana does work good on 3/70