Something good about each vendor:
Triton: The least likely to report extremely small values that are actually inside their margin of error from zero/undetectable. Some people are annoyed that they report zeros/not detected when others give numbers, but this is actually commendable. I.e. the least low concentration noise.
ATI & FM : I like their price for the data quality they provide - most of the time.
ICP-Analysis: very cheap. Until you consider the hobbyist expense in time, effort and additional tests to find out a concerning test result was a false alarm. (Ok maybe I don't have something good to say about each vendor.)
Oceamo: Nobody has been as open with data or done more to demonstrate quality and expertise than Christoph. The higher price is well justified, IMO.