Best 845 tube out there?

Assuming that the supplied 845 for the Cary 211 uses 3.5 amps of filament current then a Shuguang tube should be used.The KR tubes use 1 amp of filament current and will be overloaded unless resisters are changed.Check your owners manual or call Cary to be sure.
As for my preference,I use the 845B.

Okay, so we are ruling out United, RCA and Amperex due to high cost. Forget about the KR845, they won't work in the 211AE. The Shuguang 845C has a lower disapisation rating than the standard 845, therefore, you will need to adjust the bias on the 211AE 845 tubes. I am not a big fan of the 845C in the 211AE.

Try and find a quad of the limited production metal plate SuperTnT 845W Noblemans which are absolute awesome tubes, but unfortunately, the production run was limited. NOS Cetron 845 also works nicely in the 211AE. I have not tried the Psvane 845, but the over sized glass and build quality looks interesting, but they have not been proven in the field as they have only been on the market for a couple of months.

The Shuguang 845B is the general tube of choice for the 211AE, notwithstanding NOS.

Are the SuperTNT 845Ws(2008) the same as the Shuguang 845 Metal Plates(2009)? I have both and cannot tell any difference between them. Sophia Electric sells the 845 Metal plates online.

Has anyone tried the 845T at Grant Fidelity?

The SuperTNT 845W "Noblemen" tubes have the same tube rating/specs as the reference RCA 845. The Shuguang metal plate 845 has a lower dissipation rating (around 70w compared to the RCA standard of 100w).