Looking for opinions on which island will suit my interests: snorkeling, great food, nice beaches, not too crowded, scenic (hilly, green), clean, safe.
-Considering Cayman, St. Barths, St. Martin, or maybe even one of the USVI.
-We've been to the Bahamas.

Which island(s) do you think have the lowest crime and have relatively low poverty?

You can eliminate the Caymans due to your hilly/green requirement.

You can eliminate St. Martin if you want low poverty and low crime.

St. Bart's fits your criteria.
St. John does as well, but not St. Thomas or St. Croix.

Tortola, BVI, especially the hillside vistas of the ocean. Robert

St. John definitely fits your specs, as do many of the BVI.

Generally, the least developed islands with fewer tourists have the least amount of crime. The poverty on "undeveloped" islands generally doesn't stand out as much as on the more developed islands because there is less of a contrast. Few to no mega-luxury resorts on the lesser developed islands, you know? That said, most of the Caribbean does classify as third world, especially compared to most Americans' standard of living. St. Barth and Grand Cayman may be the only true poverty-free islands. (Maybe Saba, too, but I'm not positive.)

Also, very generally speaking, the more scenic (as you say, hilly & green) and island is on the interior, the less noted it is for its beaches. Which is not to say that the beaches on those islands aren't lovely--they are--but generally, more arid islands like Anguilla have the most outstanding beaches.

You will find exceptions to all of these rules, of course, but these are some guidelines you should keep in mind according to your preferences.

St. Barts!!!
Excellent French cusine, VERY hilly, pristine beaches, uncrowded (no 747's only a 19 seat plane) sans casionos, tacky timeshares or all inclusives, poverty or litter. Very sexy too, unlike anywhere else in the Caribbean, more like the S. of France.
ck stbartsvilla.com

For me, similarity to the south of France would be a negative, not a positive.
Not the greatest beaches around along most of the Cote d'Azur, very crowded in most of the 'better' areas, few high quality resorts relative to the number of tourists. Hopefully St. Bart's exceeds the south of France in all these ways.

St. John or Virgin Gorda definitely!!!

But if you want to give up on the lush and hilly requirement, Turks & Caicos and Anguilla meet your other requirements quite well.

to elaborate.
Sexy, and not uptight like the former British or US Islands. All beaches, yachts and hotel terraces are classic French topfree or in some cases clothing optional. Patrolled by the Gendarmarie, who have little tolerance of "nonsense" as they call it. No poverty here. Great cusine and French goods in the shops. Out early to the bakery you see the "green men" like France going through town sweeping up the smallest bit of litter.. Deliberately uncrowded, as more than 1/2 the Guest rooms are in private villas. True paradise.

Loved St.Barts( and the South of France too). St.John is also fits your requirement but compared to St.Barts IMHO I think St.John is pale in personality and food is deffinitely better in St.Barts.Cayman is nice but flat , dry and ...bland . St.Martin , St.Thomas , St.Croix have some good features too but not as safe as the other islands on your list and do have some poverty.

you sum it up very well, me

Agree with "me" and "caribcouple" about the upside of St Barth's. The only downside in my view is the cost - very expensive. I'd consider Virgin Gorda or Tortola BVI as alternatives.

I'd have to respectfully disagree about the cost on SB. There is no tax on anything. Early to the French bakery for your baguette, quiche, croissant, and dessert for 2 about $10 or less---excellent sandwiches too to or have them pack a picnic lunch for la plage. You CAN spend a lot for dinner but there are several restaurants w/good French fare for about $20 an entree. A nice bottle of Bordeaux is less than in the US, try Blanc (white) a favorite for about $7-10. No jackets required like uptight British Islands, and some beach clothing is optional too...