The AX909G2 has been marketed by several other names. It has a reputation for failure of it's plastic parts, excessive amplification - prone to overloading and wildly over-stated range/performance claims. I can never recommend it.
The EZHD has a better reputation. Also consider the RCA ANT-751.
It sounds as if you are fighting multipath, the signal from the transmitter can bounce off of one or more surfaces then arrive at your antenna just a bit later than the signal that travels the direct path. Moving the antenna and a more directional antenna are the primary options when trying to find a way to receive more of the direct path and less of the reflected signals that will arrive from the side of the antenna.
The CS2 is a very good UHF antenna. The ANT-751 and EZHD will be a slight improvement over the CS2 in terms of directional ability, they also have high VHF ability the CS2 does not. Your apt. manager may not allow a larger, more directional antenna on their property... However the FCC is on your side:
http://www.fcc.gov/guides/over-air-r...n-devices-rule You have a right to install an antenna on the property you rent.