As a reasonably active member of the HT Goa forum, I said I would post a report comparing the two destinations. We had intended returning to India for a third year running but at the time of booking getting a VISA for India had been made far more difficult than in previous years as applications had to be made in person. Consequently, lots of people had the same dilemma. The Gambia seemed a comparable choice so we decided to give it a go.
This is a summary of some of the major points that we found.(Prices for two)
Gambia doesn't require VISA's.Save £80
Gambia requires Malarone. Cost an extra £60
Gambia advises Yellow Fever. Cost an extra £100
Holidays to the Gambia appeared cheaper. Our excellent 3* hotel was vastly superior to our Goa or Kerala one's.Save £350 plus
Gambia is a 6 hour flight. Save 5 hours.
Gambia is the same time zone.
Weather is similar.Gambia in January about 31-35 cent
Beaches are far less populated in the Gambia, even the areas by hotels.The busiest resorts in Gambia are small compared to BAGA/Calangute
Gambia has far less rubbish.
Neither have that many "excursions" to places of interest available.
Cost of a taxi for the day is similar.
Hassle from the locals is more evident in the Gambia than India.More professional beggars or "bumsters" by far.Begging is frowned upon in India.However,I got used to it pretty soon and it didn't present me with a problem.
Gambia has higher prices for food and drink. Probably twice the price, but still much cheaper than Britain. Hygiene standards in restaurants seems better though by and large.
Gambia's airport and immigration is vastly better than India.
Which is better as a destination ?!

Only one way to really find out.
Try both !!!!!!!