Sooo many to choose…after rolling many tubes the ones that sounded best to me in my DAC are listed below. Brent Jesse is a good source but some what pricey. Deals can be found on EBAY from reputable sellers by experienced buyers.
Mario Miniwatt (France Philips) E188CC(7308) - rare and pricey
Valvo Red Label E188CC (Amperex Holland)- also rare and pricey
Amperex 7308 (usa) E188CC (Holland) 60’s-70’s
Siemens E88CC 60’s-70’s
Amperex 6922 (usa) E88CC (Holland) 60’s-70’s
Amperex ECC88 Bugle Boy 60’s - to my surprise these sound really close to above tubes. Best buy and readily available. Best value that I have come across in my mind.