With these embedded devices its pretty hard to speculate on the future as for which is the best as there are basically 2 forks in the road going on.
Projects like Kodi and LE are focused on following the future by moving into the mainstream kernel which represents a better method of supporting different hardware which goes outside just the perview of linux on embedded devices like the typical Android boxes, and in doing so has been removing pieces of code that were based on the vendors bsp's which tend to be done in a out of tree manner specific to themselves... In this case Amlogic is the mostly mentioned in this thread. Doing so has meant some pieces of the overall setup need to be either fixed or outright created and its mostly being done by various open source groups which takes time. hence some things at this time still need to be fixed.
The alternative approach taken by projects like CE or AE or any of a number of other forks is to try and maintain the devices by using parts of the older vendor packages which has 2 basic effects to it... one is that basically a number of devices still currently work ok with the current Leia version while two being stuck on some older packages such as the kernel and some of its support packages. Currently running on older stuff like this seems like the better way as overall it pretty much works, but once Matrix is finally released who knows where it will leave any of these distro's that took this direction.
There is just no way to know when or even if any of the issues will be fixed as overall things appear to be going in the right direction but its been a long road and the end still hasn't been reached yet.
Its probably best to look to buy based on what your current needs require rather then try and make a purchase based on how long and good some device may be like you typically would when make a normal computer or laptop.
The only way to avoid this whole mess is to basically just give up on trying to run a JEOS system like LE or CE and stick to running the Android version that came on the device as then whatever the devices abilities are can simple been seen by reading the spec sheet of the device to see if it supports the features you want.
People need to remember... Companies like Amlogic Rockchip and others never intended for anything Other then Android to run on Their device which is what the device makers paid for in support and IP licenses. Its NOT until people try and run Linux that most of these issues really have any relevance... but if you really want Linux then its either pick a distro like CE which works but is vested in older vendor packages (which will eventually break) or pick LE and make sure to buy a device that is currently supported by LE for the time being.