To be honest, I wouldn't dare to touch SQ or SHOP as a long time investment at their current valuations. (Yes, I know this sounds crazy from a guy who would consider a crazy YOLO bet instead, but I would at least be aware that this is a crazy bet ...) 

I'm following SHOP for quite a long time already, though, and always thought: This is too expensive now – nevertheless it went higher and higher which made me wuite crazy. I'll be the first one to admit, too, that I may not comprehend the huge growth potential of Shopify, which may make then a bargain even at current valuation, but as I am simply not able to "get" if the stock is a good buy right now or ridiculously overbought, I keep my fingers away. Similar thing with Square.