You could try to speculate on currencies like anon said, but I'll leave that to the speculators. Here's the technical advancements of a few coins and how they differ from bitcoin.
Bitcoin was the first, but it's got serious technical problems that can't be fixed. At the same time, it's "too big to fail", if faith in bitcoin falls, all the rest of the cryptos will too, regardless of technical improvements.
One of the technical problems with bitcoin is that bitcoins are not fungible, that is, a bitcoin can be tracked. You could, for example, have a list of "stolen/illegitamite" bitcoins, and force honest merchants not to accept these bitcoins. Monero fixes this problem by making it impossible to track which coins are sent to whom in a block, this makes it impossible to maintain any sort of list, all Monero is created equal. Technically, you could do the same kind of thing with the bank note number of USD, but of course nobody does 'cuz that would be real inconvenient. Some people suggest that with cryptocurrencies it would be more convenient and so we make our crypto fungible.
Another of the technical problems with bitcoin is that it was structured so that a new block is mined about every 10 minutes, this means, on average, it'll take 10 minutes for a transaction to "go through". But wait, there's more! You don't just want to see your transaction go though, you want to wait for 2 or 3 blocks to be built on top of it so you're fairly confident no one else is working on a different but still legitimate version of the block chain. Imagine going to the grocery and trying to pay with Bitcoin, it will take you 30 to 40 minutes to check out. I'll also nitpick >>7801
post, the "fee" associated with crypto transactions dosen't go to a bank, it's a bounty you put out to encourage miners to put your transaction in the next block. Dash "fixes" this problem by making the time to mine a new block about 15 seconds. There's really no technical achievement here, it's just a faster, less popular bitcoin.
"Bro, what if we put
"Smart contracts" on the blockchain, and then paid other people to run the programs with crypto, attached to the program?". Kinda a neat idea, but until someone really finds a good use for it, it's a novelty. I'll also mention that Etherium is supposed to be switching to a Proof of Stake system, we'll see how popular the fork is though.
Proof of Stake
A way to build a blockchain, not a cryptocurrency onto itself. instead of guessing numbers to build the next block and get rewarded with the fees + a set amount of the coin, a
validator is chosen randomly(ish) to create the next block, there are no fees involved and instead the validator and everyone who checks their work receives a flat commission for creating the bock or attesting to it's correctness.. Being offline when you're asked to create a block or disagreeing with other people validating the correctness of a block looses you crypto.
My personal favorite at the moment is
Cryptocurrency tied to other assets, these could be other cryptocurrencies like Bitcoin, non-crypto currencies like USD or Pesos, physical commodities like Gold or Silver, or any other asset. It's totally not a cryptocurrency though, it breaks the "trustless" rule that all other cryptos have, instead you trust a set of asset brokers that you can buy or sell derivatives from, think of it more as a decentralized group of stock brokers than a cryptocurrency.