Almost everyone here will say to go with MSE
My reason is that I have done BSODs. The only av that has not been the cause of one is MSE. I use it so do most others. Its made by the creators of Windows for Windows

Hello, if i were going to use a paid , i would use the best. In this site are listed results of tests for paid programs. notice on pages 8,9,10 and 11 the results. http://www.av-comparatives.org/image...od_aug2011.pdf

If i were going to use a free, i would have to go with MSE, as i have seen it work personally, one day i was testing out a site while in Sandboxie, ( a free program) which is a good program to use , if you click on questionable sites, as you can get out of danger quickly without infecting your PC hard drive. and while testing this one site, MSE grabbed an I-frame malware and what impressed me is that is detected it before my paid Malwarebytes did.

Stay safe !!

I would not waste my money on the pay AV, unless you want extraneous features. The free are just as good or better than the paid.

Yes, it has to updated many weeks when first installed. You will not have that problem. It updates automatically, when you use it.