I'm going with Bitcoin as well. 99.9% of the altcoins I look at...

I'm going with Bitcoin as well. 99.9% of the altcoins I look at are get rich quick schemes from the devs which produced it, and/or have major security flaws. As soon as you get around to pointing out these enormous security flaws, they're onto the next crap coin.

Most Altcoins / Forkcoins suffer from some serious flaws I've noticed and I'll point out below:

Bigger block sizes / Shorter block times
To the simplistic technologist or noob, this sounds great. Bitcoin is the 'Dinosaur' which can't upgrade. However, there are several cumulative negative factors of centralisation introduced by these ideas:
* Larger initial download size of the Blockchain for nodes, increasing market barrier to entry (Assuming that they got to Bitcoin's historical use and volume)
* Larger Hard Drive space required for storage of the Blockchain
* Larger amount of Bandwidth per month required to keep a node running
* Increased market barrier for miners with lower speed internet connections, still downloading the current block, while other miners are already hashing that block

Tragedy of the Commons
Phrase which refers to a limited resource being overused to the point of failure. The traditional analogy is of a paddock with too many livestock feeding on the limited amount of grass on the field. After a while the grass is consumed and the paddock turns to mud and much of the livestock die. With cryptocurrencies, they can increase their speed or size on the base layer to the point where you only have to trust a few participants, however this system now requires equal trust to the traditional banking system with similar security risks.

Bitcoin's limited Blocksize and long block time enable it to establish a market cost on the limited resource (Block space). It is important that there is a cost on the base layer, because it is a limited resource, and people would overwhelmingly chuck junk inefficiently down it if there weren't (As previously observed). As a result of cost, participants begin to use the base layer more efficiently (Now being observed). On top of this, you can build systems which allow the transaction of Bitcoin many times quicker and cheaper than could be possible on the base. This is identical to how TCP/IP for the Internet scaled. The base layer is a broadcast common layer for participants, and the upper layers enable more directional greater features on top of the base. Many, many payments can then be conducted cheaply, while still being on top of the Bitcoin base layer

IOTA

I won't go into the latest garbage coin up currently, but I will point out some major flaws with this one that has been floating around for a while now:
* Uses Ternary base math (3 Base) on computer systems natively designed for binary - This introduces unnecessary complexity which invites security flaws because the entire ternary base system has to be emulated.
* A new cryptography had to be designed to work with the Ternary (3 Base math) system. This is bad from a security standpoint because the cryptography was not well tested with limited reviewers (Less eyeballs). Since then, collisions have been discovered with the cryptographic protocol. This happened with SHA1 at the start of 2017, and it is now considered broken.
* Bad actor within the Open Source community - Has an MIT open source license, but then they use something they call 'Copy-protection' to protect from other people copying the code (The antithesis of an open source license).
* The security model to protect against attacks is far weaker than Bitcoin's on an enormous scale. Bitcoin uses live hashing to protect against bad actors. At the time Satoshi was suggesting this, many did not believe that even this would protect Bitcoin against bad actors overwhelming the network with a 51% attack. IOTA uses on-demand hashing, so that it is only secured when you conduct a transaction, not from miners mining all the time with specialised hardware. In addition, the attacker only needs 33% instead of 51% for an attack. To protect against this enormous security flaw, a trusted server known as the 'coordinator' is used with proprietary code (The antithesis of Bitcoin).