Switch ahead of PS4 so far. However PS4 had a pretty good software lineup for the first 5 months of 2016. Switch hasn't really had anything special yet this year (except Mario Maker 2 which just released a few days ago). If Switch is selling this well with no special releases so far this year, then imagine how well it will sell for the remainder of the year.
Switch is about to have a very solid second half of the year in regards to software. It's already outpacing PS4. It's about to shoot far ahead. These numbers are very telling. PS4 is a very strong selling system, but the Switch is about to shoot far ahead.