For average students you can prefer VMC ( I would recommend atleast try for Pitampura or Anand Vihar).
As per FIITJEE Kallu Sarai it has mixed reviews. For above average students it has served very well. But for average or below average it hasn't, as mainly in lower batches of FIITJEE they don't give focus to students also they don't provide good teachers.
P.S.: Reviews taken from my friends who have attended or have been attending.