  We compare several well-known cosmological dark energy models using
observational data coming both from type Ia supernovae and from Hubble
parameter measurements. First we use supernovae data to determine the free
parameters of each model except for the Hubble constant $H_0$. Then, we use the
Hubble parameter measurements to determine $H_0$, and finally the age of the
Universe for each model is computed. Our main numerical results are summarized
in tables, and they are briefly discussed. The prediction for the decelerating
parameter as a function of red-shift for each model is shown in the same figure
for comparison. Our numerical results seem to indicate a correlation between
the deceleration parameter and the value of the Hubble constant.
