I would go with the max fan.....quieter than the Can 10". Beleive it or not the loudest is my 6" HO Can. I have an 8" max and its sooooo much quieter. Google their website and you can see what each fan is listed at. They measure the perceived loudness in "sones". Not sure if Vortex has this info on their website or not but I can only attest to the difference between Cans and Max Cans because that is what I use.
I recently went to my local hydro shop, before purchasing my 8" fan, and compared several brands of 8" and 10" fans. I found elicent to be the quietest, imo, for both sizes.
In my experience the Can Max series are the quitest, but like opm45 i have only used other can fans. The thing is the max were A Lot quieter than the regulars cans. I like to go a size bigger than i need and put a controller on it to slow it down as a fan running at full speed is a lot louder than a fan not.
i just ordered a sunleaves wind tunnel 6" fan for 140 shipped. its 410 cfm vs the 440 cfm of vortex, but its made of plastic instead of metal so it is supposed to be much quieter since there is no vibration noise. uses alot less watts also. i got it for my 3x3 400w veg tent, should be plenty. i get it next week.
also what worked wonders in my flower room, was hanging my vortex fan from bungy cords. if you do that and use insulated ducting, it will help alot. Also wrapping the fan in insulation like others said.
elicent. hands down the most quiet 10" available. not the most powerful, but there usually is a trade off between cfm and dB. the can max 10 is way more powerful and not much louder aaaand you can put it on a speed controller to slow it down and make it more quiet. elicents don't like standard speed controllers. vortex is good too: slightly more power and slightly more noise. If you can afford it and you NEED the extra cfm I would get a 12xl vortex and neck it down to 10" with a speed controller.
i'm a bit confused on what loud is concerning these fans. i'll be using grow tents which will be in a bedroom which shares a wall with the neighbor (duplex apartment) . if i use one 4" and two 6" can fans for use with carbon filters and then 3 more can fans to insert fresh air into the tents and finally 3 fans to cool the lights via my sunmaster hoods (along with all the ducting), could he hear the fans running through the walls? i will keep them as far from that wall as possible.
i've grown for years but never had to mess with fans and filters other than a couple table fans to move air around in the closets.