Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

• dpkg: low-level (without deps manageent)
• apt-get (and apt-*): low-level (with deps management)
• apt: user friendly
• aptitude: even more user friendly
• ~~wajig~~: use apt or aptitude instead

Overall, apt and aptitude are recommended.

aptitude

aptitude why pkg explains why pkg is to be installed.