C++

1. pointer (but sometime, we really need it, I know)
2. semicolon
3. compiling tasks (I couldn't compile a complex program by cmd for once)

Python

1. Explicit self parameter for methods breaks symmetry with functions.
2. Legacy Python 2 still default in things like MacOS Sierra. The __future__ module is neat, though, and #coding:utf8 at the top fixes Unicode issues.
3. Style guide stuck in the '90s. (4 space indents, 78 char lines)

Dart

1. No optional parameter in function type definition: typedef void Handler( int required, [ int optional ] ); is not possible
2. Small community
3. Inconsistent behavior of integers between Dart VM and dart2js

Java

Can't have checked exceptions in lambdas. >:(

Python is awesome. Buuuuut:

• Although it has one of the coolest import systems out there, python still have serious problems with cyclic imports. Other languages handle it muuuuch better.
• It creates .pyc files for bytecode caching that are just annoying. PHP also caches bytecode and never needed to polute the working tree. Common python :p
• Packaging a python library is just stupidly hard. After doing it in python, I couldn't believe myself when I did my first npm publish. So. Much. Easier.

My current favorite, even though I am still learning it, is Rust.

1. Confusing naming conventions :(
2. Messy lifetime notations
3. So many things I am not allowed (by the compiler) to do in safe-mode, making me shout at my screen very often

Ruby as a language is really beautiful and gets a lot of things right. But a few aspects keep bugging all the time:

1. Magic global variables from perl legacy : $!, $@ etc.
2. Prevalent practice of autoloading constants - javascript finally got this right with ES6 modules. Explicit imports are verbose but they are amazingly helpful when trying to read through code.
3. Logical operators - we have both and, or etc. and &&, || with different operator precedence.
4. Lack of a good interactive debugger - pry comes very close but is difficult to use in large codebases. No good visual debuggers like the one built into chrome.
5. Ternary conditional operator, an unwanted legacy from c-esque languages - in a language where if-else is an expression - there is simply no need for this to exist.

Python

1. Choosing whether to support Python 2 or Python 3 even though now more people are supporting Python 3.

2. Packaging software is still not as intuitive and straightforward as other languages.

3. Lack of GUI libraries. PyQt and Kivy are good but I want more options.

Clojure

• Slow boot, JVM is heavy, people joke about it.
• nil, like we have in JavaScript, but it's 1/4 the trouble since there are null and undefined in js.
• the community is too small, lots of problems are not covered like js did

I don't really have a favourite language but lets got for PHP (7) because it's the one I know best.

1. inconsistent order of function parameters
2. no real data structures (structs)
3. missing variable scoping

Javascript

Some small annoyances.

1. NaN !== NaN
2. Hoisting
3. Classes are confusing to new people.

Java

1. Nothing
2. Nothing
3. Nothing :) Odd situation: front end job applications made better offers. Go JavaScript ftw

JavaScript

1. Semicolons
2. Automatic Semicolon insertions
3. Getters & Setters

Go

1. Versioning system should be baked in the language.
2. Extend a go program without bringing in the whole source and recompile.
3. No optional parameters on functions.