Looking to expand my BTC mining setup and invest a couple bitcoins more.  Is there any other better alternative miner than Antminer S1 at this time that anyone knows or can recommend?  Antminer has been the better option for on-hand equipment for some time, but I have started to see other options, wandering if there are other concrete options now.

Still prefer to avoid pre-order companies, but may be willing if wait time is no more than a month.

Appreciate any feedback.