No tubes are "best". It depends on the circuit you are using them in and on your hearing preferences. On the other hand, Mullard and Telefunken, also the Amperex bugleboys are the most popular (and costly )amongst audiophiles. Mullard has manufactured for a lot of other tube makers and Elevick is right, generally it says made in Great Britain, which by the way can be ( and often is) easily forged. Mullards also carry a code near the bottom of the tube, for example Xf1 for EL34s or 7L1 for E88CCs.
