Recommended tubes for LTA Preamp

Hi All - 

I recently upgraded my LTA Microzotl preamp to the Level 2. I see myself having this component for a long time and don’t anticipate ever wanting to replace it. 

I’m planning on purchasing some back-up tubes for it, though. I was wondering if any LTA preamp owners out there wouldn’t mind sharing their experience with different NOS tubes for the LTA.  LTA currently has Brimar and GE NOS tubes in stock, but wanted to see if anyone might share their own experiences tube rolling with the LTA preamp. 
 

Thanks in advance!