What frequency range do you want the best reception on?
I have an 800 Mhz omni with a 3dbi gain about 25 feet at my location.
I have it multicoupled to 4 scanners. I mostly listen to our statewide 700/800 system as well as an adjacent county's 800 system.
It work great for me.
All antennas work on digital and analog. If someone is advertising the antenna as a digital antenna I would be skeptical.
Not a great answer. First see what you mostly want to monitor and the frequencies. If it is all over the place, VHF,UHF, 800, I would consider a discone, it gives goo rx over the entire spectrum but only at unity gain. I have had good experiences with discones in the past. Have one packed away, just no real estate to put it on at the moment.