What sucks in Ruby, and why X is better in some other language
A critical look at our own tools, frameworks and idiosyncracies, and an opportunity to talk about something cool from our other favorite languages.
Bonus: We can also have fun defending our sacred cows.
Kyle Shipley commented
Some other higher-level ideas:
Implicit vs. explicit
Open classes vs. e.g. Clojure's protocols
Monoliths vs. microservices
Mixins vs. composition
These don't require deep knowledge of other languages to have an interesting conversation, although knowledge of other languages / development styles might help inform your opinions.
Go - Binaries compiled are statically linked to be cross-platform, no worries about system libs.
Erlang - Concurrency and resilience
JS - One-language stack
Many things - Strong typing
Swift - playground editor?
Smalltalk - tight editor/vm integration
Scala - customizable macros
Haskell - Pure functions & Immutability