If you are looking for the "best tool" for the Lenovo U1, you are likely looking for one of the following three solutions, depending on your role (System Administrator vs. End User).
Officially, the Lenovo U1 Tool (sometimes called the “Lenovo USB Utility Tool”) is a low-level firmware flashing and device repair utility. Unofficially? It’s the master key to Lenovo’s digital basement. lenovo u1 tool best
For Think-branded machines, it typically executes the ThinkPad Maintenance Utility . If you are looking for the "best tool"