Given that I know the leathers well, I would like to weigh in if I may.
Black crash is lighter and thinner. As Jenova says it is not a soft smoochy calf, more a crinkled glossy surface with some texture.
Black glossy is slightly heavier, smoochier and rather than a glossy wrinkled texture it has a semi-glossy pebbled texture. It feels more like a thick soft leather.
They are completely different but the main difference would be the weight. Whilst the black glossy is not heavy, it is heavier than the crash.
Both wear extremely well. I have a friend - if you email me I will send a picture of her but I think it is in the gallery somewhere - who has the TME midi in black crash and it is actually the only bag she presently owns. It goes everywhere and has done for about a year and it looks the same as the day she bought it. My black glossy pebbled hug me also looks the same as the day I bought it.
So I would make your decision based not on how hardwearing it is but based on what is your top priority? Lightweight?; Choose Crash. Smoochiness?: Choose Glossy; Look: either I love them both. Price: Crash is more expensive. But only a bit.
Jackie XOX