I'm fairly certain November is the wettest month of the year on Roatan. Not that you won't be getting wet diving but it affects the visibility. If you decide on Roatan, stay south, diving in the West End/West Bay can shut down if there's a "Norther" while you're there. A couple years ago my friends were in one over Thanksgiving, many of the West End shops shut down since their pangas can't get out. The bigger operators (Anthony's Key, Coconut Tree, West End Divers - others) move their boats and shuttle you over. Roatan has one shark dive - the only place you'll see them and the Dolphins at AKR.
Bonaire is easy diving - shore diving capital of the Caribbean. Many dive resorts are waterfront and offer both boat and unlimited shore dive options. It's often flat calm there. The East Side is the only spot with rougher water and fast currents - wait till your buddy has more dives. There's easy shore dives off almost all the dive resorts - many on named dive sites - and up and down the west coast. Farther north some of the entries get a little more difficult and almost all of them require good treaded boots and some sense of balance as you're often traversing ironshore/coral rubble at the water line.
Curacao is the same diving with easier entries - off sandy beaches instead of over the ironshore. The few that are on ironshore have dive docks. Dive sites are farther spread apart though. There's almost as many - something like 50+ compared to Bonaire's 70. Most of the known dive sites have on-site facilities, operators, snack shops etc. On Bonaire once you leave the dive resorts there's no facilities of any kind. To try shore diving Curacao also has the Dive Bus - they do escorted shore dives. It's a good way to start then go out on your own. We did One boat dive the entire week on Curacao (20+ dives) and about 6-8 on Bonaire. 4 would've covered the Bonaire highlights IMO.
There is about 10X the things to do on Curacao, casinos, nightlife, famous shopping downtown - also 10X the population. Curacao might be cheaper/faster to get to from Ontario. The West End of Curacao is surprisingly very quiet - most people live near Willemstad. Most of Bonaire is quiet.
Since the reef on both islands parallels the shore, navigation is simple. I never used a compass once. You swim out to the ball (slightly longer swim on Curacao), decide which way the current (if any) is going and swim into it. With a few exceptions on Curacao's west side, at most sites you'll be able to see your entry point during your entire dive. Or just look for your vehicle, on Bonaire's south side it's parked 20' from the water.
Both Bonaire and Curacao are primarily small stuff. Lots of live coral, small fish, crustaceans etc. About the biggest thing you'll see are Stingrays, Moray Eels and lots of Tarpon. Curacao has a Dolphin dive also thru Ocean Encounters. We saw dolphins twice in the wild from our balcony but never in the water. I've never seen a shark off either island.
I believe from your area, Cozumel will be the most reasonable. I don't know much about it. It is typically deeper drift diving so that may be a lot of task loading for your buddy.