to choose best antennas

what is your application..............
still the most basic parameters are
VSWR
frequency of operation
polarization
power handling capability
gain
temperature
application
environment
field of view
maximum allowable dimension............

---------- Post added at 12:43 ---------- Previous post was at 12:04 ----------

Radiation pattern: The relative distribution of radiated power as a function of direction in space – an (hypothetical) isotropic antenna radiates equally in all directions.
Gain G : The ratio of the radiated power in the maximum direction to the radiated power of an isotropic antenna. The gain of an antenna represents the ability to focus its beam in a particular direction – an isotropic antenna has a gain of 0 dB.

Radiation Resistance RA: The equivalent resistance which would dissipate the same amount of power as the antenna radiates.
Input impedance ZA : The ratio of the voltage to the current at the antenna terminals (Thevenin equivalent circuit).
Polarization: The direction of the E-field.

Beamwidth: The angle between the two directions in which the radiated power is half of the maximum value of the beam.
Bandwidth: Half-power frequency band.
Antenna efficiency: e = Prad / Pin
Effective aperture: It describes the effectiveness of an antenna in the receiving mode. It is defined as the ratio of the power delivered to the load to the incident power density.

my application is mobile antennas