I dont think the lotus looks to bad myself! I think it will be very quick as its been in the making for 8years! and you cant say them dont know what there doing!!!
The Virgin car imo looks very poor on aero, it seems very basic, not alot of fins, wing modifications or vents like you seem on most other cars. I also think the Renault looks very poor.
I think just by looking the top runners will be:
Mercades,
Mclaren,
ferrari,
BMW,
and mabey even lotus