St Lucia or Guadeloupe?

Hey everyone, I’m currently planning travelling around the Caribbean but could really use some insight of where to choose if anyone could offer suggestions please!

I’m going to Dominica for a week and to Martinique (my flight is out of there) but after that I’m not sure whether to go to Guadeloupe or St Lucia. Here are my current thoughts:

I don’t have time to go to both so I was thinking maybe St Lucia as I wondered if that would be more different to Martinique than Guadeloupe would be? Also I know very little French so thought two French speaking islands back to back might be tough.

But I’m on a backpacker budget so didn’t know if St Lucia would be too expensive? I’d be using public transport and other than potentially a chocolate tour wouldn’t be looking to spend any money on activities (I’m thinking beaches, wandering around towns, maybe some small hikes)

If you have any thoughts I’d really appreciate it, thank you!