To be fair, in the first book, EUOL hasn't really described the rules of Feruchemy as well as he has Allomancy. For example, we know that to collect Feruchemical power, you have to spend time being weak, or tired, or whatever the case may be. But we haven't really been exposed to the process, beyond the occasional hinting with Sazed. Also, we don't know if there is a limitation on how much Feruchemical power can be released at one time, as I recall. And, we still don't know all of the Feruchemical powers. However, judged on the information we have been given, I think I would rather be a Mistborn for a few reasons. For one thing, it would be much easier to train yourself in Allomancy than Feruchemy, because you wouldn't have to have a large refractory period wherein you would have to be weak, blind, etc. You also don't have atium, emotional allomancy, or the ability to push and pull metals. That takes away the ability to "fly" and it also takes away one of the primary offensive weapons, meaning that, short of throwing things, a Feruchemist is strictly melee. This wouldn't be a pretty significant disadvantage in and of itself, but it also means that they are less mobile, so they won't always be able to get at the target they want. Beside that, you saw what Kelsier did to that last Inquisitor with metal.