All depends on where you fish and what kind of range you need. If you don't tend to venture too far off shore where you would need many miles of range, just about any VHF antenna on the market will be sufficient. If you do need extended range, compare the "db" rating on the antennas available to you. The "db" rating is basically the amplification factor of the antenna, and the higher the rating, the more range the antenna will give you. Mounting the antenna as high as possible will also increase your range.
Hope that helps!