The Lact-Aid is better in several ways. I have used it a lot, but also used the SNS quite a bit, too. One of the best things about the Lact-Aid is that it is much easier to conceal under clothing and a lot less noticeable while you are wearing it. I really liked the fact that I could have one all ready to go, in the fridge, with the neck cord all ready adjusted. I could just grab it and pop it over my head, unwind the tube and get it in place and get the baby latched, without even having to put the baby down. When the babies were tiny, I would take the chill off the milk, but all that entailed was putting hot water in a drinking glass and holding the bag in it for a few seconds. The two tubes of the SNS make it seem like it might be easier because of not needing to move a tube to switch sides. However, because of the two tubes, which are twice as long as the Lact-Aid tube, and the way that the SNS has to be hung upside down and the tubes positioned in a specific manner, getting set up to nurse with the SNS requires two hands and takes probably 4-5 times as long to get set up with. When you have a baby screaming to be fed, every extra second can seem like a long time, especially if it is the middle of the night and you are hoping to keep from waking everyone else up.
Another thing is that the SNS is harder to use without taping the tubes. With the Lact-Aid, it often helps to tape the tube when you and the baby are very first learning to nurse but, after that, there is usually no need to tape. The problem with tape is that even the gentlest kind gets to be pretty irritating when you have to keep taking it off over and over.
I am extremely thankful for the Lact-Aid, which made it possible for me to nurse my six adopted babies, the last four of whom were able to self-wean, which they did at an average of about two and half years old.
Best wishes to you!