Well, bitcoin is the best crypto and considering the current market it would be the best choice. On the other hand, i really don't have much idea about Iota.
Bitcoin is always an option in crypto investment. but, I might share the money for 4 crypto, bitcoin, eth, xrp, and bch. well, the coin is a very good coin, and stable enough to be stored in the long run. besides, bch coins are also good for short-term investments.