Actually Oliver's real personality is more of the funny type, just like Felicity. If you look at Ollie during pre and on island he is a lot like a "male Felicity", he is a lot more serious now because of trauma but even in the present day he still has a good sense of humour, and has laid back and funny personality is coming back a bit more with time. Fandom loves it when two characters have contrasting personalities, but lol they actually get it wrong with Oliver/Felicity, their personalities are actually a lot alike. The show actually got it right, with Oliver/laurel, Laurel is the "straight man" in the relationship while Ollie is the funny and goofy one, a bit like in the comics. So no Felicity doesn't actually work better with Oliver for that reason you started, its actually the other women, Shado, Laurel, Mckenna as L.Is who works well with Oliver for that reason, and Felicity as a friend.
Exactly, Digs is a lot more of the straight man than Ollie. And I would say Slade as well.