The "selfloop" product is a box that you have to connect to the phone with a USB cable. That seems inconvenient.
You'd have to decide whether you want to have something stick out of your phone while riding. Note that you can use a cable between the phone and the dongle/box/whatever.
I saw the ANT+ USB sticks while doing my search but I think they are designed to upload the information stored in the ANT+ storage device directly to a PC. If there is compatibility with Android OS and will work with the ANT+ sensors directly then that would be great but I didn't see that being mentioned in the product descriptions. Garmin has a version of a USB stick and there are aftermarket versions as well. No indication I could find that they make one designed to work with an Android ( directly with the ANT+ sensor ). At the moment other than the "Selfloop set-up" I mentioned I don't see any other options. Hopefully that will soon change.
The Selfloop set-up does look bulky but is no more bulky than if you already run the phone with an external battery. Now if there is an ANT+ USB stick available, being less bulky that would be preferable but then you probably wouldn't be able to hook up an external battery with the stick in the way. (?) That's probably why the selfloop included a battery. Personally I'd rather just have a stick as long as the app's that run all this stuff don't drain the battery down too fast. That would be the question to ask before buying anything.
Also note that Wahoo is gauging interest in a version of the RFLKT that includes an ANT+ bridge to allow ANT+ sensors to be monitored via BTLE/4.0 smart phones. See the kickstarter here: http://kck.st/1ap1j2C