Antennas for FM Tuners in Urban Setting

Is ST2 omnidirectional or directional?
Would a directional antenna mean choosing a direction and therefore getting great signal with certain channels while limiting the total number of channels I'll receive compared to omni?
Unclear at the moment but I might be able to mount on the roof. If not it looks like the ST2 could be mounted right outside a window. 

When is the approx. distance from the transmitter(s) to your residence?

The ST-2 is omnidirectional. With a directional you have to point it towards the station you want. IMO, a directional is so much better!
http://www.magnumdynalab.com/st-2-omnidirectional-fm-antenna/

   I have four McIntosh tuners..they all perform great with a ST-1

Finding a good antenna involves trial-and-error.  Many overlooked antennas outperform their counterparts.  Many factors are more important than the antenna: station proximity, your building, what is in your building ... .  Many times an inexpensive properly placed antenna outperforms an expensive poorly placed antenna.