Suggestions for titlesec
The following packages have something in common with the package titlesec. The packages are ordered in decreasing similarity.
- titleps: Page style control
 - fwlw: Get first and last words of a page
 - titlefoot: Add special material to footer of title page
 - underlin: Underlined running heads
 - clrdblpg: Control pagestyle of pages left blank by \cleardoublepage
 - nccfancyhdr: Extensive control of page headers and footers
 - continue: Prints ‘continuation’ marks on pages of multipage documents
 - fancyheadings: Legacy headings package
 - autofancyhdr: Automatically compute headlength for fancyhdr package
 - chifoot: Chicago-style footnote formatting
 - rplain: Redefines the plain pagestyle
 - sfheaders: Sans headers
 - fancyhdr: Extensive control of page headers and footers in LaTeX2ε
 - scrlayer-fancyhdr: Combining fancyhdr with KOMA-Script’s scrlayer
 - endheads: Running headers of the form “Notes to pp.xx-yy”
 - updatemarks: Extract and update marks from boxes
 - scrlayer-scrpage: Define and manage page styles
 - scrlayer: Manage text ‘layers’ within Koma-Script
 - floatpag: Different pagestyles on float pages
 - hackthefootline: Footline selection and configuration for LaTeX beamer’s standard themes
 - scrpage2: Control of page headers and footers in LaTeX
 - biihead: Underlined page headings
 - floatnohead: Suppress page headings on float-only pages
 - headerfooter: Define the layouts of page headers and footers
 - titletoc: Alternative headings for toc/lof/lot
 - uwa-letterhead: The letterhead of the University of Western Australia
 - alnumsec: Alphanumeric section numbering
 - anonchap: Make chapters be typeset like sections
 - coseoul: Context sensitive outline elements
 - alphanum: Sectioning commands for jura
 - chbibref: Change the Bibliography/References title