Honestly, if you were to remove any I would remove kraken and coinbase, they are both the same and horrible when it comes to depositing fiat, if you want to deposit crypto and trade crypto and withdraw crypto then there is absolutely nothing wrong with them and you can use them (even though they have HORRIBLE interface) but when it comes to depositing fiat currency into them it becomes like a hurdle and really can't be sustained at all, they always delay it, they say its coming, they say its banks problem not theirs, basically they do everything and anything under the sun they can possibly do to use your money for a while before they let you use it as well.

I doubt they use it for interest rates or whatever but it takes ages and sometimes you have to call your bank and report it so you can maybe get it back and bank asks for it from them.