The Precision is the one to buy if you can only get one. The Precision 910 is a great tester for older radio tubes (not newer tubes really). It is "dynamic" and not emission. It tests the tube more like it is in circuit than an emission tester does. The Weston 774 is an emission tester. It's cool, but it is just a go/no go tester for emission. That said, Weston made good gear and I love anything with the 4/5/6 pin socket that their testers used. Neither will test 9 pin miniatures.