You'd need to tell us more about the overall installation.
Specifically;
Where the antenna is being mounted?
How big an area are you trying to cover?
Are you trying to provide coverage for mobiles, portables or both?
What is your budget?
What is your skill level?
I'm sure others can come up with a few other questions.
There isn't one antenna that works for every situation. Picking the appropriate antenna takes some work, analysis and even a bit of trial and error. Due to the cost and risks associated with putting up an antenna, I'd strongly consider that you talk to a qualified installer or radio shop before doing anything. Especially finding one local to you that understands the local topology, interference and coverage challenges.