why not just buy an Antminer S9? It would likely be just as profitable for around the same price, and it's at the top of it's game for efficiency. There is less of a chance that there will be another Bitcoin miner released within the next year that would make the S9 obsolete. I can't say the same for the L3+, A4+, or Dash miners for that matter.
I also believe that mining good old fashioned Bitcoin with an S9 would be the most profitable out of all of the ASIC options mentioned above unfortunately.
You seem to be correct. I am currently considering to order a few new miners, and incline to S9 - because of the current good return, and in particular because BTC price will most ikely to continuously rise in future (with some drops of course) than other coins (to my opinion).
But after D3 disaster (which i thoughtlessly bought a few units), I am too afraid that some company would invent much more efficient miner than S9, and same scenario repeats as with D3. Why do you think this won't happen with s9 in near future, or within a year at least?
Herein lies the risk associated in the mining game. There always has, and always will be these types of risks involved in mining crypto.
I'm not saying that it's impossible that the same thing won't happen with the S9 in the future, but I do believe the chances are much smaller that it will because of the fact that companies have been trying to make the most efficient Bitcoin miners for 8 years, where as companies that have been focusing on LTC and Dash had only gotten serious about it recently (of course LTC has been in it for a while.. but still relatively new) so the limit as to how much hashing power can be physically stuffed into one miner cannot yet be measured as well as with Bitcoin miners. The S9 uses (almost) the latest and greatest technology even by todays standard, using the 16nm mining chips that are the smallest, most efficient cost effective chips out on the market.
The mining chips used in Bitcoin miners have nearly hit the 'Moore's Law' Wall, meaning that
exponentially more efficient mining chips are no longer possible to produce, meaning that what we have inside of the S9 is (almost) as efficient as they will ever be for a while. Yes, China has announced a bitcoin miner that uses 14nm mining chips (basically the smaller the nm number, the more efficient they are..) and yes, they will probably make a more efficient miner, but only to a certain extent. Right now it is much much harder / more expensive to create anything that would be efficient enough to make the Antminer S9 obsolete.
Even Andreas Antonopoulos has said that the chips will lead to extended shelf life of mining equipment because of Moore's Law.
http://blogchain.info/post/14nm-chips-will-re-decentralize-mining-says-antonopoulos