What's a good VHF/UHF ham radio antenna?

I will be purchasing a Yaesu FT-7800 dual band VHF/UHF radio in the next couple of weeks.

I am seeing all kinds of antennas being advertised with different connectors (N-connectors, PL-259 plugs, BNC and SMA fittings). They are quoted at various dBs of gain, and different wavlength designs. It is confusing.

Does having a higher DBI get you better range? And does buying a longer antenna mean you are going to get better receive and transmit signals?

I will be purchasing a vertical antenna for the two bands and was just looking for a little bit of help to understand what these things actually mean when you are operating the radio equipment.

The set up will be mobile, in a vehicle.

Are cell phones dangerous to children?