Choose a platform that has the best liquidity. There is no point launching a coin and there being no one to buy it or sell to.
Nxt has the highest number of assets, widest variety of buyers and has had over $15,000 of trades in the last 24 hours and over $770,000 trade in the last 30 days (Av. $25,000 / day). There has been an average of over 300 trades a day, every day, since the day of launch in May 2014*.
Liquidity is key for a healthy coin. Look at coinmarketcap, hundred of coins while most barely trade at all. They are zombie coins with bagholders, a sorry hangover from 2014 splurging.
Nxt Monetary System takes the hassle out of creating your coin and it can be exported from Nxt at a later date, if something else is a better fit. They can be minable too, if you want a POW distribution. In the next release, they will be shufflable too (so anonymous). And it is already in an established ecosystem. Take a look when weighing up your options.
*
http://nxtreporting.com/assetcap.php, scroll to bottom for sources of info.
Nxt assets have already been listed on Polo and Bter. Monetary System Coins will follow. I have asked what was required from those involved in the listings.