Trains when possible.
I've been riding motorcycles on and off for years. For the last 8ish months I've been riding one of those like city share electric moped/scooter things. It's a cheap Chinese NIU brand. For the size and state of infrastructure in my current city (Tbilisi) it's honestly the best way to get around.
I lived in Tokyo for years though. I would take a train network like that any day of the week.
Certs are a waste of time tbh. If you have 8 years of experience, you should have more than enough to fill out a resume already.
An AWS cert is almost certainly even more useless for you specifically unless you wanted to get into devops/sre and do systems design. I have been in sre for a very long time and have never even heard of anyone writing tooling in Java. That section of the industry is entirely dominated by go, python, and (more often than anything else) bash for really quick automation.