How you choose one machine and one company seems tough.No doubt.
David12 (Threads | Answers)
Each modifier has a house sound, IMO. Once you decide what sound you like, then trimming the list of possible candidates becomes easier.
For my taste, Modwright's sound is detailed and extended, yet warm and organic, especially using Sylvania GB-5687 tubes. Empirical Audio is extended, accurate and hyper detailed. Exemplar is also accurate, extended and detailed. APL HiFi is extended, detailed and natural.
Also, some companies provide you with a detailed list of the parts and labor that comprise the work performed. Some companies do not provide this information. You have to decide which approach you prefer.
Finally, customer service carries a great deal of weight. This forum has several discussion threads on the topic of customer service regarding modders.
Good luck. The research, and the modification, will be worth the effort.

