I put down a 3 for the ease of the water change. At one point I was against AWC as I was not a fan of automation. I do not like not knowing what is happening. I feel like the more I get into automation in the hobby the more I feel as ease with it and want more. One day I will have an AWC, but for now there is no place to put the containers to keep the fresh and waste water.
For now I am still part of the "bucket brigade" and to be honest I dont mind too much, I like maintaining my tank, I like the testing, the cleaning, the upkeep. Ok, so I am an odd ball...
I have a SW mixing station in my garage. 210 gallons of SW and 210 gallons of FW. I prep the RO/DI as needed, usually when it gets down to about 20 gallons. (I have a 7 stage RO/DI system). I mix Tropic Marin Pro by the bucket, about 165 gallons per bucket to get it to 35ppt. I do weekly water changes, via bucket, usually on Friday's. On the Wednesday or Thursday before I fill the 5 gallon jugs with the water and bring it in the house to cool from the garage (Warm in the winter) to be ready for the change.
Once I start the water change it takes about 12 minutes to do a 14% water change. At that time I change the filter sock, clean the skimmer cup and empty the Trident water container. That adds a few minutes. All in all I am done in 20 minutes, tops.