Custom Post Types and Custom Taxonomies

Probably the best way is to use the help of code generators and manually enter PHP. example

or maybe the best way is to use class libraries like johnbillion/extended-cpts by respected author. For example, you can register a post type or taxonomy in one line.

Generators:

Generate Custom Post Type or Taxonomy
Meta Box Custom Post Type & Custom Taxonomy Generator

In order of first-look quality:

Very extensive plugins:

Ultimate Post Types + Ultimate Fields are nice plugins, but they try to sell too hard.
Types - Custom Fields and Custom Post Types Management

This is a beautifull plugin, but not sure if it’s exactly for the same purpose: CPT-onomies: Using Custom Post Types as Taxonomies

Poorly designed & disqualified plugins

These plugins are NOT even aware of already existing Custom Post types:

Custom Post Type UI

Converting Post Types and Taxonomies

Switch Post Type, Change Post Type, Post Type Change

This is

Post Type Switcher has everything, and here is an article about it.
Ima i ovaj, ali nudi i Pro verziju što me odmah “naježi”: Post Type Transfer. I naravno, nema čak ni opciju da promeni Post type kroz “Bulk Edit”. Bez veze.
Convert Post Types is beautiful plugin for mass-editing of Post Types.
Taxonomy Switcher

Hierarchy plugin will solve a problem of editing and entering Custom Post Type data. Isti autor je zatim napravio plugin OrganizeWP - Fix Content Organization in WordPress