Nxt, as mentioned, as has terrible distribution. There may had been 73 original wallets but only 20 wallets invested the 1.5 BTC limit (this was before the November boom). I'm going with a haunch, since it was such an obscure IPO without taint analysis, that those 20 wallets were probably only owned by 5 people with sockpuppet accounts.
IIRC - people who invested 1.5 BTC had received either 40 to 50 million NxT. That means there are easily sockpuppet masters with close to $14 million USD in NxT. These people will be billionaires if NxT rivals Bitcoin in capitalization (even wealthier than Satoshi).
Ethically - the last coin I would invest in would be NxT, you're contributing to some whale's get quick rich fund.
NxT did attract an amazing community but it all went down south after people realized how screwed up the distribution was and the solution resulted in NEM, which is entering open Alpha by June 25.
NEM has been distributed to 3000 stakeholders and taint analysis was used to remove hundreds of sock puppets. There may still be sockpuppets in NEM but, realistically, it's an unprecedented unparalleled distribution compared to every other coin in existence.
Every coin is dominated by less than 50 real people (more often it's less than a dozen people, the developer and his friends).
NEM is unprecedented and will launch with several thousand stakeholders. Even if there are 200, 500 or 1000 sock puppets (unlikely due to anti-sock puppet measures), NEM still has thousands of real unique persons. That is compared to the average crypto these days where a dozen or less people own everything.
There are a ton of haters of NXT because of its distribution. But hands down NXT is without a doubt the slickest thing in crypto right now and by far the best thing to come along since Bitcoin. Ripple is up there too but is not a coin and is more of like a payment transfer system.
Monero/Blackcoin/Cryptocoin are nice and are also better than bitcoin in many ways as far as what is under the hood, but won't do anything much that bitcoin can't do now or will be able to do in the future. Right now some seriously well connected and intelligent hackers/developers are making "dark wallet" for bitcoin. It is in alpha now and can be downloaded and played with. When it comes out, it will give anonymity to bitcoin. At that point people will have a choice, use Blackcoin for anonymity or Bitcoin. One of these has a huge network, tons of connections and tons of end points for users. One doesn't.
Any bitcoin clone is a one trick pony. Those clones often just add one feature. If said feature is really important and people like it, it WILL be incorporated or hacked into bitcoin someway. This is a very slow process.
NXT on the other hand has lots of features. Right now it has aliases, leasing of NXT, fast block times that are meant to get much faster, messaging, an asset exchange and much more, and much more coming soon. All that and in a nice package. Right now it has high fees, but that should come down later. Anything that any other coin can do, NXT can and probably will incorporate. For bitcoin, it has to be a big deal for it to be added, but for NXT, everything can be added and is being added that people want. One thing NXT can't add though, is a good narrative of how it started. Many pros on this forum won't touch NXT despite it being leagues ahead of the rest.
That is where NEM comes in. Yes, it hasn't come out yet, and the first Alpha Alpha for testing won't be out until June 25, but it does have serious developers, as in as many as 8 working on it right now. Not one dude like many of these other "privacy" coins. NEM code is written from scratch too and unlike NXT is being tested and tested part by part so that it will be very easy to build on. Devs regularly post their test outputs. On top of that, the NEM community has done everything very transparently and cleanly. I am seriously putting my money on NEM, and when the big shots that constantly cry that they won't touch NXT because it wasn't "fair" look at NEM, what can they say? Actually, with NEM having up to 3000 holders, I am thinking that many of the old timers crying foul about NXT slipped in and got a share of NEM themselves.