When considering an alt-coin, I would first ask the following questions:
1) What problems / issues does Bitcoin currently face?
2) Does the alt-coin address these issues, and if so how?
Bitcoin currently faces two main issues that prevent its widespread use as money:
a) Bitcoin cannot scale at the protocol level, otherwise known as the blocksize issue. The current Bitcoin blockchain is limited theoretically to 7 transactions per second and in practice to around 2-3 transactions per second. For comparison VISA can peak at well over 40,000 transactions per second. Furthermore this limitation in Bitcoin will not be overcome by technological improvements in processor power, network bandwidth, digital storage, etc since they are baked right into the protocol. As of this point I have not seen a solution for Bitcoin that addresses
both the scaling of the blocksize and the security of the network once the emission runs out.
b) Fungibility. As more and more companies are getting into "Bitcoin blockchain analytics" and selling their proprietary "solutions" to industry participants there is no guarantee that one's Bitcoin are going to be accepted in a transaction because some proprietary algorithm alleges that one's Bitcoins were used in say an illegal transaction
N transactions ago. This is not an issue with cash and a digital cash equivalent needs to have at least the same level of fungibility as cash.
If one looks at the top 20 crypto currencies, that are both proof of work and whose primary purpose is their use as money,
Monero is the only one that fully addresses both of the above issues in Bitcoin.
Monero addresses (a) above by using both an adaptive blocksize limit combined with a tail emission. A tail emission would break a critical social covenant in Bitcoin making this solution impossible in Bitcoin and taking the tail emission out will make the coin insecure as the emission runs out. This is the fundamental problem with the design of Bytecoin for example. Dodgcoin does have a tail emission and could add Monero style adaptive blocksize limit with a comparably minor change in the social covenant but at this point has not done so.
Monero addresses (b) above by using a very elegant mixing method using ring signature that allows instant mixing with existing transactions on the blockchain. This avoids the need to use a second level of mixing servers (Coinjoin in Bitcoin, Dash masternodes) that introduce both delays (it can take hours or even days to mix Dash) and a very significant regulatory risk associated with the operators of the mixing servers.
To get the real picture on how the market has valued Monero over the last 2 years I would suggest taking a look at the historical market capitalization
https://coinmarketcap.com/currencies/monero/#charts rather than just the price. This will account for the fast falling emission rate in Monero.
