.... which one you would like to choose if u only have the choice between BTC and IOTA?
I never think about another coin while BTC is option. BTC has first ever decentralized cryptocurrency and after that, all the coins came in the market. And because of this thing, BTC has a massive effect on other coins and it will be manipulated to other coins. If the price of BTC has started gaining then the market will appear green and when BTC started losing its price that time all the market become red. So things kind of massive effect has BTC on other coins.
So always choose BTC over any coin. It has high potential in its growth. If you make your mind right now to making an investment in it then you will definitely make a huge amount of profit in the upcoming period of time.
Although IOTA was able to become the top 15 in coinmarketcap to date, I think IOTA is only an altcoin which of course can be a choice of recommendations to be used as an alternative investment. Another with Bitcoin that has been trusted by everyone is able to become the best cryptocurrency that can provide benefits to its holders