Top 10 guitar makers

When taking a packet to my home last week, the delivery man asked Liz if this is the same Sobell as the guitar maker he delivers to in Whitley Chapel.

Liz told him yes.  Then he told her his mate was into guitars and had read in a magazine that Stefan Sobell is one of the top ten builders in the world.

Clearly an excellent magazine, with at least one very perceptive journalist. Can anyone tell me which magazine it is?