With Teams, you are limited to the number of connections you purchase. Basically, you used to just buy connections for FileMaker Go and WebDirect, but with the new Teams licensing, FileMaker Go, WebDirect, and FileMaker Pro are all included together. Because of this, you are probably spending less on individual FileMaker Pro licenses, but getting the flexibility that a 10 person team, for example, could all use FileMaker Pro, FileMaker Go, or WebDirect. So lots more flexibility and probably cheaper if you do need those FileMaker GO and WebDIrect connections. However, if anyone has a licensed copy of FileMaker Pro (Legacy style), they can connect to your server without using a connection seat.
With Legacy, it's really good if you don't need the other two technologies, because you only have to pay for FileMaker Pro and Server. FileMaker Server 16 does still have one concurrent connection from my understanding.
I would see what use-case you fall most under than price out the two different packages of Teams vs Legacy and see if one gives you a better bang for your buck.