Great choice in speakers!
This is rather tricky for anyone else to give a definitive answer to. From the options you've mentioned I'd say you simply have to place it where is sounds the best. Tricky to acchive at times, I know, but it's the basic rule. The performance of your subwoofer will greatly depend on it's placement and the room itself, just like any other speaker. This is especially true if you do not have a good calibration/equalizing system to compensate, but even then placement is still essential. Compromise is difficult to avoid though, unless you have a dedicated room built from scratch.
My personal advice before settling for a permanent placement is to try out different locations, if possible, during an evaluation period to see which one works best for you. Here's a little tip: buy/borrow extra long subwoofer + power cable if needed (just to use for testing) so you can easily move the subwoofer around without restriction. Just don't forget to run a new calibration procedure after every adjustment (if you intend to use such) otherwise the sound will be unbalanced.