Excellent show to rewatch. You know what I find funny? Is how the showrunners (Berlanti, Kreisberg, and Guggenheim more than Mericle) have all said they take their cue from BtVS. But if I had to pick a Whedon property they are 'spiritual successors' of, it would be "Angel". Why? Well, let's take a look. 
Main character is a tortured, brooding anti-hero who only cares about his mission initially - Check with Oliver/Angel.
MC gets a 'conscience figure' who is at first male but then switches over to a woman - check, just Arrow took longer for it to happen than Angel. This was Diggle/Felicity and Doyle/Cordelia, in case anyone's wondering. 
MC finds himself building a team that gives him a connection to his humanity: for Angel it was Doyle, Cordy, Wes initially. For Oliver it was Diggle, Felicity, and occasionally Tommy/Laurel/Thea. 
Somewhat budding romance between MC and female conscience figure/pop culture guru for the first two seasons: Angel/Cordy build up matches with Oliver/Felicity build up. 
Third and Fourth Seasons has the MC and his new love interest having an angsty, tortured romance that simply won't work out because the love interest eventually can't be with the MC due to their penchant for secrets or because of seeing who they really are: Angel/Cordy have a problematic relationship due to Darla and then Connor, and finally Season 4 happens and anyone whose seen that knows the crapstorm that happened. Oliver/Felicity may ride off into the sunset in Season 3 of Arrow, but eventually Felicity decides she can't be with Oliver because a part of him will always be the man who returned from the island to save the city on his own, akin to Cordelia telling Angel she can't be with him because when she was a higher power she saw him as Angelus. Now, some people explain this away as being what's her face, Jasmine... 
Finally, one theme is that at first the titular hero is the one calling the shots and people follow his lead, but eventually they are marginalized on their own show and while everyone can heap abuse on the titular hero, criticizing the female lead is akin to devil-worship.