I have four portable scanners, but the one I use the most for aircraft is a Uniden Bearcat BCD396T. It can monitor UHF military air channels, which most handheld scanners can't, and I also have it programmed for the local police and fire departments, so I can listen to those if I want to.
Actually, at DVT, where I go most often, they have monitor speakers on the observation deck for both of the tower frequencies plus ground control, so I don't even take a scanner there. It can be somewhat confusing though when there is a lot of traffic, which is often, and all three freqs are active at the same time.