Tali is a better (or at least equal) hacker.
You must be joking.
My ideal crew (by which I mean the best people to have on the Normandy, not necessarily restrained or defined by squadmate designations). Clearly this isn't gameplay focused.
Miranda- XO, war planning
Kasumi- Infiltration expert
Tali- Engineering
Mordin- R&D, Medical
Garrus- Weapon Master
EDI- Cyberwarfare
Legion- Geth terminal (direct line to geth allies)
Joker- Pilot
Chakwas- Medical
Adams, Ken/Gabby- Engineering
Ashley- Ground team
Vega- Ground team
Javik- Ground team, war planning
Traynor- Communications Specialist
Cortez- Shuttle Pilot
Typically only those marked ground team would be what now counts as squadmates. Squad lead would be Javik or sometimes Garrus (Shepard learned Delegate!) On cases where Shepard is away Miranda has command. Most of the other roles are self explanatory. Legion's inclusion is because the geth are left as your biggest allies at the end of ME2 if you do his LM (before ME3 fucked it up). EDI may use her body in some situations or to accompany Joker but is otherwise in standby. Kasumi typically runs solo missions. There would also be a direct QEC line to Liara as the SB.