For VHF, choice of polarization is not up to your desired radiation pattern, but who you want to be able to communicate with. In HF, the ionosphere causes random rotation of your signal's polarization, but in all line-of-sight communication, VHF or higher, there is no such rotation and a polarization mismatch can result in no signal at all.
You should use vertical polarization if you wish to communicate with existing FM mobile and repeater stations, because they also use vertically polarized antennas (by convention, and because quarter-wave verticals are much more convenient than other types of antennas on vehicles and handhelds).
On the other hand, you should use horizontal polarization if you are attempting 2 meter SSB or other types of DX/weak-signal work. Again by convention, but the convention arises because (if I understand correctly) horizontal dipoles typically have more gain, and because a horizontal dipole is a simple, efficient freestanding antenna.
If you wish to be able to communicate with both types of stations using a single antenna, you can use a diagonally or circularly polarized antenna, as a compromise which has a reliable small amount of loss in either case. However, such antennas are more directional than a vertical (at least as much as a horizontal dipole) and thus require pointing.