L3+ is definitely best for now. But if you look at network hashrate for the most popular coin - Litecoin the total hashrate is equivalent to about 57k L3+ so when a lot more L3+ come online or if somebody else releases more efficient machine profitability could drop a lot. By comparison Bitcoin network hashrate is equivalent to almost 800k S9's so if somebody ships 10k units of twice as efficient miner it will hardly make a dent so S9 while less profitable seem like a safer bet. Obviously it also depends on con price and other factors. At the current price at $1265 S9 seems reasonable.
Some people are still bidding £2.5k+ for D3 on e-bay when the payout is down to £10/day. I did actually bid on L3+ on ebay that is in UK already and used for 6 weeks but missed by £3 because of earlier placed bid. If I buy one from Bitmain now for end of November delivery it will cost about £2100 with power supply, shipping and taxes. I reckon if i had one now it would make £500-750 before that so I am looking to buy one for around £2.5k or less.
I have also been looking at other options and while Nicehash is the most profitable most of the time sometimes you could be better off mining elsewhere. But Nicehash is pretty much set and forget so it does not take any of your time. If I were running a large farm and gave up my day job it might be beneficial to follow and to point it at different mining but for hobby Nicehash is probably the best most of the time.
Then I came across
https://www.miningrigrentals.com/ where you can basically rent out your rig and set the price you want with a fallback to another pool. Looking at Scrypt the average payout on Nicehash have been 0.0078BTC/GH/day and the cheapest available o rent on
https://www.miningrigrentals.com/ was 0.00811 so a little better. You could set your price at 0.008 to get customers nicehash as your secondary pool so that if nobody pays that you still keep mining on Nicehash. I think i will try that out.