I can't even post 5 "promising" cryptocurrencies. Beside Bitcoin, I am using only 2-3 altcoins, because I believe in the potential of the projects, the technology used and the team behind. I am not looking for pump and dump coin, I plan for the long term usually. I read the white paper and make my own opinion
Bitcore BTXBitcore has one of the lowest transaction fees on the market while possibly providing the best on-chain scaling solution in the entire crypto-sphere
The SegWit blocksize is 20MB while the average blocktime is 2.5 minutes, the max supply and the Proof-of-Work block reward halving time are similar to BTC
HorizenHorizen is a blockchain platform with a leading-edge privacy technology that provides everyone with privacy and complete control of their digital footprint. We have a sustainable funding model with protocol-level solutions.
For me the most promising cryptocurrency is only bitcoin because the price is quite good and the early investors made millions of dollars in bitcoin. The prices of other currencies are low; therefore the profit is also low. If you are looking to any other crypto then I suggest Ethereum and Ripple because these two are the fast growing cryptos in the market and also promising.