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.
I would go for coins with a great prospect of growth and they are Bitcoin, ETH and Binance Coin. They are the killer coins and can really give back great returns. Especially the accelerated pace at which they are gaining value is impressive and I am sure there could be a more than 4X return or gain if you HODL till the market reach to the apex.