If your using win7 mse (microsoft security essentials is free) but should never be used as your sole anti-virus , for free ones I use avast.
Malwarebytes should be used & spybot only use when you need to address a problem not day in day out.
For a paid for a/v I would recommend Kasperky , one of the best imo.
ok theres a few i have tryed i perfer avast with smart defrag advance system care 5 and Ccleaner and something i use here and there is iobit malwarer fighter with that i find for systems maint that combo works very well