How to keep up with packages and know which ones are obsolete?

Here's a list of possibly obsolete packages and classes, and recommendable successors. It's not intended as a judgement – it's supposed to help in choosing packages or checking preambles. Readers can make their own decision based on the package documentation of the compared packages.

• Obsolete package(s): Recommended successor(s)

• a4, a4wide, anysize: geometry, typearea

• backrefx: backref
• bitfield: bytefield
• caption2: caption
• csvtools: datatool
• datetime: datetime2
• dinat: natdin
• doublespace: setspace
• dropping: lettrine
• eledmac: reledmac
• eps, epsfig: graphicx
• euler: eulervm
• eurotex: inputenx
• fancyheadings: fancyhdr
• filecontents: No successor (included in the LaTeX kernel; see filecontents: This package is obsolete)
• floatfig: floatflt
• german: babel / polyglossia
• glossary: glossaries
• graphics: graphicx
• here: float
• hyper: hyperref
• ifthen: etoolbox (see Why is the ifthen package obsolete)
• isolatin, isolatin1: inputenc
• mathpple: mathpazo
• mathptm: mathptmx
• ngerman: babel / polyglossia
• nthm: ntheorem
• palatino: mathpazo
• picinpar: floatflt, picins, wrapfig
• prosper, HA-prosper: powerdot, beamer
• ps4pdf: pst-pdf
• psfig: graphicx
• raggedr: ragged2e
• scrlettr: scrlttr2
• scrpage, scrpage2: scrlayer-scrpage
• seminar: powerdot, beamer
• sistyle, siunit: siunitx
• subfigure: subfig, subcaption
• t1enc: fontenc
• times: mathptmx, txfonts, txfontsb
• ucs: inputenc, inputencx with utf8 option, see utf8x vs. utf8 (inputenc)
• utopia: fourier
• vmargin: geometry, typearea

I took the list from my TeX blog where I started to maintain it some time ago, for sharing it here. It's in form of a list, since tables are not supported on SE posts. Feel free to suggest edits.

If you search on the CTAN catalogue, many obsolete packages have notes pointing to the newer packages they have been superseded by. For the particular example of subfigure, its catalogue entry has to say:

This package is now obsolescent: new users should use subfig instead.

Whenever I find about a new package, I tend to have a look at CTAN before using it to watch out for any of these notes and also quickly browse through it's documentation.

Actually subfig isn't maintained anymore. I would use packages like »subcaption« (shipped with caption) or floatrow. A good list of obsolete packages and other outdated stuff can be found in l2tabu.