What type of soffit vents to add?

I recently had my roof redone and went with a ridge vent along both my house and detached garage. The problem is I have vented soffit on my house but my garage has nothing. I have one gable vent that i plan on blocking off after I install the soffit vents. Im just wondering what is the most common way to go about putting these vents in without replacing the soffit. I dont want to mess with the existing siding as its pretty new and really nice. Im debating on whether those 2-6" round pvc vents would look better in the soffit or just add the regular rectangle ones. Im thinking the rectangle ones will look tacky just screwed to the exitsting unvented soffit. Im leaning towards just gettting some of the 3" round white ones to match, and putting me a few of those in...opinions?