Your alternatives to Roatan are Utila (c29 km) or Guanaja (c70 km) from the Honduras mainland port of La Ceiba.
Both are of course also surrounded by vast coral reefs with prolific undersea life and diving/snorkeling is their mainstay for visitors. Utila is known the smallest of the major islands in the group and claims to the least expensive. They were "discovered" by Columbus in the early 1500s and later settled by Cayman Islanders (which is partly why both Spanish and English are spoken there). Guanaja has no roads and locals travel by boat, including a channel which islanders call, "the cut", allowing access from the south side to the north without having to go all the way around.
Utila claims to have over 60 different scuba diving sites, including caves and numerous wrecks (such as the famous "Halliburton"), and is also famous for divers encountering whale sharks when they migrate past the islands (the whale shark is the world's largest fish at 12-18m, a slow-moving and harmless zooplankton, snapper egg, and shrimp eating fish which grows up to which is quite majestic to behold close up.
At the SW end of Utila are a small collection of tiny islands, some just 100 feet across and 1-2 feet above sea level. The 2 main Cays, Suc-Suc (Pigeon) and Jewel Cay, are inhabited by local fisherman and the descendants of the Cayman original settlers who arrived here from in 1836.
There’s a regular passenger ferry running twice a day from La Ceiba or you can fly on one of several daily flights (not all of which are direct).
Both islands are far less developed than Roatan and don’t have the same numbers of chain outlets or large-scale hotels (though there are some luxury resorts and their number is increasing quite fast). You’re much more likely to hook up with a local than a new-ish arrival as most are run by local families or people living here.