Don't worry about what's "obsolete". Worry about what you can use to achieve your goals. If you want to build webapps on an AS/400 using RPG/IV, then go for it. This industry is already way too "fad driven" where everybody is walking around thinking that only the latest, shiniest, newest, cutting-edge, "whatever" matters.

That's not to say that some tech doesn't have more merits than others, but you don't necessarily have to worry about always using "the cool thing of the day".

All of that said, I primarily use Groovy + Grails, Postgresql, Bootstrap, and jQuery for building webapps. For backend microservices I mostly use Java with Spring Boot.

Yes, there are "sexier" things out there, but this stack lets me accomplish my goals, and I know it well and am very productive with it. And for me, that's what matters most.

Tired of being that guy who has ideas but can't make them a reality.

If there's a stack you already know well, I'd say stick with it. If not, I'd suggest picking basically anything reasonably modern/mainstream for webapps. So, probably not actually RPG/IV, or assembly, etc., but anything that's used in this domain, and where there is plenty of documentation, community, etc. to support you. Use PHP, Python/Flask, Java/Play, Scala/Play, Node.js, Ruby/Rails, Groovy/Grails, Drupal, Joomla, etc.