I hated Rachel's ending. It was awful, rushed, and it felt like the writers didn't know what to do with her because of Finn/Cory passing away, and having Jesse back was so random.

having Samchel was forced and unnecessary to happen. 

Her going to back broadway after quitting and after what she did, was wrong, and being Klaine's surrogacy was a wrong writing choice too especially after the Shelby fiasco.

Here is what I would have done...

Please don't take my ideas

St Berry isn't endgame at all

Rachel does not get with Sam at all. But they are still good friends

Instead she has a secret affair in S6 with Skylar the warbler. It's reasonable. It's not creepy and there's not a big age gap like Puck and Kitty.

and since Skylar wasn't there when Sam was unnecessarily the glee teacher it would mean that Skylar was actually 18. Plus Rachel wasn't legally a teacher like Shelby was when Puck was hooking up with her. So technically speaking Rachel and Skylar are not illegal at all.

Rachel is the glee teacher. She does not leave the position at all. 

Jesse does not randomly come in and take her away from a position that she really loves.

Rachel has Puck help her be the glee teacher not Kurt.

Rachel also gets her teaching degree officially and majors in music and the performing arts.

Rachel also performs on the local stages part time and asks the director if the glee kids could be the extras or other characters in the musical.

She focusses on herself and her mental health and cuts ties with most of the glee members including Santana, Quinn, Brittany and Mercedes. Which to her is the best thing.

She is not the surrogate for Klaine at all. That's Quinn instead no matter how much Kurt pressures Rachel. She will stay no because of everything to do with Shelby and Shelby not wanting her.

Rachel becomes a singing teacher for McKinley too. She carries on Finn's legacy. and finishing what Finn had started, because she knew what she was doing. 

She is either single, with Puck or with Sebastian or Skylar

If she is single: she would never be with anyone again because of her heart being with Finn. (Even though I do not ship Finchel) and she would show and represent that you don't need someone to be happy. (The difference with Mercedes showing that than Rachel. Mercedes can always go back to the guys. Rachel can't go back to Finn)

If she is with Puck: Friends to lovers. (again favourite trope) They fight to get Beth back. and they co parent Beth with Quinn. The ship that is a risk taker. They love each other but can't be together.

If with Sebastian: Enemies to friends to lovers. (My other favourite trope). Sebastian and Rachel's story would be star crossed lovers. Met as kids, grew up together. They secretly always met up in highschool. Rachel slept with Sebastian through West Side Story to portray Maria perfectly. Sebastian challenges Rachel but also makes her happy. Rachel is at peace with Sebastian.

If with Skylar: They are forbidden love. they represent that it's okay to be scared together, but its also okay to be a secret. they would face hardship but they will face it together.

Rachel does not go back to Broadway.

She realises how awful Finn did actually treat her, and seeks therapy to heal.