It should've been Quentin Lance
With it being 10 years since Guggenheim made one of the worst decisions in the Arrowverse I wanted to give my reasons why I think Quentin lance should've been the one in the grave.
It would make a little more sense why Barry would show up at Quentin's funeral than Laurel's. Barry and Laurel barely knew each other at that moment and i don't think they had a single conversation directly with each other. But Barry met quentin at the same time he met Oliver and they had a least one scene talking to each other. admittedly this isn't a strong reason but I thought I should at least bring it up.
They have an established reason on why he would die. One of the main problems I have with Laurel’s death is that the doctor said she'll be fine and then the next scene she's just coding without explaining why. Quentin has had heart problems since the finale of season 2 and it was so bad that Laurel was worry that telling him about Sara's death would make it worse. so him coding because of his heart is believable.
him being gone is the reason why the SCPD is so easily corrupted in season 5. it was already corrupted but with quentin being dead adds to how important he was to the police station and to the city and how dire it that he is gone. also having the anti crime unit being people that quentin trusted to most would've hit so much more. he might be gone but his spirit is in the ACU.
quentin death would've been the push that Laurel needed. Quentin and Laurel have experience so much together with Sara dying and dinah leaving and sara being alive and dying again and being revived. the lance family have been through it and those too have been rocks for each other. and having quentin died the only person who's been there with her during all of that trauma would be a different kind of grief. and there's so many directions they could've taking her after that.