Definitely new here but been doing Youtube for a couple of years now. The whole time I've been making videos my work schedule has kept me busy enough that I maybe get one video out a month. I spend a fair amount of effort planning my videos to try and maximize the quality of the video since I don't get a whole lot of time to work on them. Looking around here it sure seems like a lot of people are going for the quantity approach and I'm just curious, if you have to choose between quantity and quality which would you pick? Obviously having both quantity and quality is the most ideal but most people aren't in ideal situations.

For myself I swore that I would never just throw together a video for the sake of chasing viewership and that I would only ever do videos that met my standards. But that's just me.

-Garage Science
I would pick quantity, because you can upload a good video once a month, but no one will subscribe because you don't upload frequently and so on.
In terms of appeasing to YouTube's system, you HAVE to have both. But the matter of "quality" is subjective. A video that might take you only an hour to make can be horrible quality to a cinematographer while also being amazing quality for someone that just wants to hear you talk about random things. Knowing your demographic and the type of content you can get away with "minimum" quality for the sake of greater content frequency is the winning formula.
I would pick quantity, because you can upload a good video once a month, but no one will subscribe because you don't upload frequently and so on.
Same goes for quality content a lot people wouldn’t want to subscribe if the content isn’t good, I usually go for once a week but I was sick so I couldn’t upload for two weeks because I couldn’t even get out of bed to edit my video. I would say uploading once or twice a week in beginning so you can have a decent amount of time to make quality content and you also have content that people can watch. Uploading once month may cause people to not want to subscribe because they think you don’t really upload. I had someone advertise their channel to me and they only had two videos that was few months old so I didn’t subscribe because I figure they really don’t make content anymore.
Depends what you define as quantity. uploading everyday, every second day? All depends on you, time is a very important factor in how much effort you spend on making videos. If you like quality do that, if you like quantity do that! Remember that you doing this for yourself, enjoy the process.
YouTube's suggested videos system definitely rewards quantity. But viewers usually subscribe because of quality. If you put out very frequent poor quality videos that people don't watch for very long YouTube will penalize you anyway and you'll just be wasting your time. Some channels are able to grow just fine putting out an very occasional masterpiece, but those channels usually have some other way of alerting viewers when they have a new video (like a good band that has a big email list and can email everyone to look at a new video for example). If you are going to focus on infrequent quality videos you can't rely on YouTube to tell an audience about them. Unfortunately.
As you mention quantity AND quality is the most ideal but it is unrealistic to many Youtubers. If you have to pick one I would go with quality at ANY time and that would be my advice to all new Youtubers. IMO you will get at better chance of getting new subscribers if you got high quality videos and then there is the watch-time issue (very important when we talk YT) and it goes without saying that watchtime is better with quality content:)
I completely agree with quality being more important than quantity. I have always thought that. I just wanted to ping the community to see if there were people that thought otherwise. It was mentioned that you still need quantity to maintain a base viewing audience but I know that my subscriber retention is very good even with the low quantity of videos I put out. I think that speaks volumes to the benefits of taking the time to make a good video. There are multiple channels I subscribe to that don't put out a new video for maybe 2 months at a time. But as soon as the new video goes up I watch the whole thing and many others that follow the channel do the same thing. Youtube rewards that and even though it makes the initial grind longer I think it's more beneficial in the long run.

-Garage Science
Most efficient system for growth I think is to find some topic or series of content that works and that you can prove will work over and over and then create a large quantity of it with "decent" but not wasting your time quality. If you've made a lot of videos you start to understand what improvements in quality actually net you a return and which ones make only make a few people happy for the extra time/money you spent.

The two aspects to quality where you do need to always go above and beyond are topic and thumbnail. Those are where you will see an actual return. If you pick a bad topic, having great equipment or editing or retention isn't going to make it a viral video because people have no interest in the topic or they won't find the video. I know quality is a very noble idea to promote but if you have a concept that works you should just make as much of it as you can rather than using that time trying to min/max your quality for very little return. Again the exception to me are topic and thumbnail.