I think the current squad looks well-rounded and condensed. I wouldn't have put EDI on it, but it looks... interesting? I think seven squadmates is plenty (I'm counting right, right?). If you removed EDI, Vega and Prothy (nothing against them I just don't know them).
I would put Jacob (in place of Vega). He's a soldiers, he's a bro, and I think he has the grounds to be a well-developed character. Call me crazy.
Instead of EDI, Legion. Seems to be a logical choice. He's a pretty plot important character who I think has potential for much more development.
And Prothy would be tough to replace since he's DLC.
Also, I might take a lot of heat for this, but I think Liara would've been better as a full-time Shadow Broker and Tali would've been better helping the Quarians. Don't get me wrong I romanced Liara, then switched and stuck with Tali. But they could be easier written somewhere else. I might move Mordin and Jack/Samara into their spots. I don't like Jack, but it makes sense. Samara wasn't developed enough in my opinion and she could use more than a cameo in this game. Maybe Thane could fit in somewhere.
Miranda is better with Cerberus
Zaeed and Kasumi are Mercenaries.
Wrex and Grunt are with Krogans.