I couldn't decide between 300s or the blueair 411 auto, so I bought both. I ended up keeping the 300s.Looks: blueairAlbeit personal preference, the blueair wins this area pretty handily for me. I like the taller skinnier design of the blueair given where I was going to place it *(.7 inches skinnier). Plus the fabric filter covers on the 411 allow it to blend in more with my decor. The levoit, is a giant piece of plastic, and it looks like it. The display on top is slick, but I leave that off most of the timeFilter: Tie, with maybe slight edge to the 411.The filter on the levoit is about twice as thick, but has about half as much exterior surface area as the 411. Additionally I think the fabric pre-filter on the 411 will probably do a better job of keeping the actual filter from having to filter large particles. I suspect the 411's filter will probably last longer due to all of this. However given the added thickness of the levoit, I bet it's filtering smaller particles better.Filter costs: Tie3rd party replacement filters for both are about the same. Although I suspect the 411 will need them slightly less frequently due to the increased exterior surface area of the filter.Exterior Build: LevoitThe 411 doesn't really have any type of skeleton protecting the outside of the filter. While handling the 411, I was constantly concerned I'd crush the filter or otherwise deform it *(and I did). The other problem with this is blueair didn't really give you any safe place to grab the 411. The levoit on the other hand is a giant solid feeling piece of plastic. Although I won't be moving this around very often there is a good chance my dog will brush into it or poke it (she sleeps next to it), so this did matter a little.Fan: LevoitThe Levoit's fan is a solid impeller type fan. When you shake the unit you don't hear any kind of play from the bearings or mechanisms. There are 4 fans speeds plus auto, (sleep, low, med, high) and auto will switch between those 4. An interesting quirk is that whenever you change fan speeds it seems the Levoit overshoots the speed slightly, and then slows the fan down from there. That doesn't really bother me though as I don't expect to be changing speeds often.The 411 however is a standard 5 bladed 6.5-ish inch fan (I didn't measure). When I shook the 411 I could hear play in the fan's mechanism. There are 3 fan speeds (low, med, high) and auto switches between them auto hereIn terms of air volume coming out of the top of the units the Levoit sleep, low and medium are equivalent to the low, medium, high speeds on the 411. That means the levoit's high is a whole extra gear higher of air movement when compared to the 411. The specs of the unit corroborate this fact.Noise: Levoit- This is by far the most important section to me.The 411 is audible even on the lowest setting (or auto), and to make it worse it has a baseball cards in bicycle spokes type noise (check out the video in my review of the 411).The Levoit is inaudible on sleep, and I often use low as white noise if I take a nap during the day. On Medium and High have the levoit does have a slight high pitched whistle, but I don't need to use those settings much.Power Use: TieI used a belkin wemo insight to measure both devices at varying fan speeds, and waited for the power draw to stabilize. The insight can not measure less than 2W and instead displays <2W. Also the 300s was connected to wifi when I performed this test.Levoit: Auto <2 W, Sleep <2W, low = 5W, Medium, 9W, high= 22W411: Auto <2W, Low <2W, Medium 2W, high 9W.As I'll be leaving this on Auto most of the time, that's what matters most to me. As both are less than 2W, my suspected running cost for both is less than $2/yr at $.11/kwh. Basically don't worry about power draw.App: LevoitIn spite of myself being a smarthome enthusiast *(I have at least 70+ smart devices, and about 25+ apps to control them all), I did not care about having another app. That being said I find myself actually using this one. It was easy to get up and running on android *(I'm a nerd, but it really just worked). The big benefit is that I scheduled the purifier to run on Medium when I'm not in the room (which happens to be my office), and then turn back to Auto before I return. When I get back to my office the air smells and feels noticeably better than the rest of the house. Plus being able to tell alexa to turn up the purifier just seems cool. It will be more useful when I stick a second one of these in my daughters room and I can turn it to low for white noise without having to enter the room.So yeah I returned the 411 Auto.