updated by @tttristan: 02/14/15 03:30:53AM
If you want modern sounds, definitely go with Fortunate Youth, or Rebelution, Through the Roots, or Smokin' Roots Crew(hard to find),
I'm more into the modern stuff, so can't really give you much help with roots reggae.
If you're leaning more towards ska, try Desmond Dekker, Hepcat, Mighty Mighty Bosstones, The Slackers
If you like or want to check out groups who have a lot of different elements going on, horn sections and a jazz feel and still that nice underlying roots eat coming through, then check out these guys, and there are a few roots groups thrown in here; Groundation, Milton Henry, 10 Ft. Ganja Plant, Fat Freddy's Drop, Yellow Man, Toya,....most of the Marley's are great, you have some different styles and whatnot amongst them.
I love the the Roots Rock Reggae (or what I like to call West Coast Dub) & Island Reggae (Hawai'ian Reggae). I have a few Hawai'ian artists posted on my page. Here's a couple of sites you can stream from, Surf Roots Radio, Maui Native 92.5 7 Q103. Yes they have competing radio stations that play reggae ALL day in Hawai'i