Tube replacement recommendations

I believe it’s time to replace the output tubes in my amp, looking for recommendations. It’s an Audio Note P2SE, 4 6n3ce tubes currently. I’ve never changed the tubes, and it seems like there are lots of options. Any advice is appreciated. 
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I see they are Russian military and well regarded. Looks like the option you have is either buy new production or buy NOS military.

The older Russian 6P3S-E are a good choice for the P2SE, but I found it hard to discern any real noticeable difference between them and the Sovtek 5881's. They appear to be an older vintage of basically the same tube. I think the earlier Sovtek 5881 had the same dimple getters as the 6P3S-E, whereas later versions had ring getters. Another nice tube for the P2SE is the new production re-issue Tungsol 5881.

I had a P2SE for 16 years and not a day goes by that I do not miss it.