Reliable: vim, Microsoft Word/Excel, SQLite, tmux, GNU coreutils, svn I think most would agree with most of the items, although svn warrants an explanation. I prefer the paradigm of git, but svn always impresses me with its ability to handle large repositories and large files out of the box without falling over.
Word and Excel are not that reliable at all. I can't say LibreOffice is much better, but all graphical office software has let me down more often than I'd like to recount.
Excel has trouble opening any kind of CSV files, let alone if they're a bit too big. Word recently got stuck in a "save loop", making you painstakingly click the "don't save" option on your work because trying to save does nothing anymore. Both examples are from the past two months.