I've used AVAST! for years. They have the a great boot scan that can go through your Windows before it boots up. I used it for XP, Vista, Window 7 and 10. It's free to try, is moderately priced but can have options added to it. If I was in high security and wanted the best at any cost, then Kaspersky would be my choice. These two companies have a vast customer base that keeps feeding them virus information everyday. This helps them develop anti-virus updates quickly and installed throughout the day.