Digital Nomads

I'm trying to plan a trip from mid-April to August. I've never traveled anywhere in this region but have started to do some research and am trying to narrow down the places I want to go. Ideally I would like to stay in one place for about 3-4 weeks at a time.
About me - I'm a 28 y/o man from California, will be traveling alone and my Spanish is not great but I will be studying a lot before I leave so that hopefully it's enough to get by in most places.
What I'm looking for - Good internet, safety walking around by myself (w/ common sense ofc), and ideally sunny weather. I have a girlfriend here so don't need a great dating scene or crazy nightlife, but I do like to go to bars and drink socially.

Here's my list so far:
- Buenos Aires
- Medllin, Colombia
- Costa Rica
- Antigua, Guatemala
- Mexico City

Should I remove any? Is there a great place I'm missing? What month(s) should I try to go to which place?

I'd appreciate ANY sort of insight, knowledge, or advice. Thank you!