I would say that neither is more common than the other. For native speakers, it usually depends on where the speaker is from. Personally, I use both - sometimes I pronounce the "t", sometimes I don't. So, I would just recommend using whichever you prefer. :) (My background: I'm a native English speaker from Texas and I have a master's degree in Second Language Studies)

Hello. We pronounce "often" with silent "t" and i think it is common.

In the US it might be where your from. In the south we slow it down and spread it out, so « how off’n you com’n by ». In the north its faster and tighter. « How often? ». Just say’n

Depends on the speaker if he's an American he'd use often without the /t/ sound, and for a British speaker he'd use often with /t/ sound, it's not up to what pronunciation is more common, it's about what pronunciation you are speaking with ;)

I agree with Les. It depends on where you come from and how your family speaks. I don't pronounce the "t" at all and never have because my family doesn't. Some of the people in my area do.