A good first banjo is likely a lower price-point open back acoustic banjo. A few examples include a Recording King RKO-3S, a Deering Goodtime, or a Washburn Americana B10. Since 5-string banjos are the most common type of banjo, we recommend beginners start with a 5-string banjo over a 6-string or tenor banjo.
However, if you’re transitioning from guitar and simply want a banjo sound without learning a new tuning, a 6-string banjo is a good choice.