amel fat tails have held their value fairly well since there is not an extreme amount of people mass producing them at this time, personally I think they are a nice sound investment and I do not see them bottoming out anytime soon.
codom snows will drop, obviously a $1000 leopard gecko will not stay that way forever. a codom in a leopard gecko can be produced much easier than most morphs, but the difference here is there are many more things to come from this morph in the future. MANY unseen possibilities. And frankly, most do not understand are know.............. yet.
Pricing on codoms may drop, but I do believe as new things pop out from our work on crosses interest in the macks will keep it from dropping as quickly as many predict. Say for instance something cool pops out from a mack bell crossing, people will want to obtain the products required to produce this morph..... demand was already there, pricing may be dropping over time, but will be increased due to new potential for example and basically keep it from dropping as quick, hold it steady, or perhaps even put them in such a high demand pricing increases. Time will tell
Both seem like sound investments at this time, personally I've invested in both. If I had to choose one, it would be the Mack Snows. There are many more possibilities with that particular investment, more potential to create "bigger and better" things.... And to be honest, its so much fun
All in all, choose what YOU prefer and would like to work with. It should really be about personal preference first, investment or profit last. Good Luck!