My Own Train vs. other 9v trains
The "My Own Train" series only lasted from 2001 - 2004, so it had a relatively short life span.  For the most part, they were very nice sets with rich details.

It most likely didn't resonate with collectors since the trains were available in various different colors, with or without a tender — this made it prohibitively expensive to own the collection since the price of the blue train was the same as the green train, and yet the only difference between sets were a few bricks that were switched from blue to green.  I, myself, bought a small and large train with tenders and the wagons, but I didn't bother with all of the other colors.

The other minus for the "My Own Train" series was that it didn't include any mini-figs, so it made it felt geared toward adults and yet, they weren't any more challenging in building than normal 9v trains.