Easily the BENGALS.
Owners are notorious cheapskates... everyone involved in the football operation gets paid lower than their contemporaries.. execs, scouts, coaches, and players (free agency spending)
That's one of the reasons Marvin Lewis was kept in place for so long, he was willing head an underpaid coaching staff (including himself).
Hence why even when they were good and making the playoffs they didn't spend in FA to become even better. So they'll always be a lesser version of what they could be.
They'll never do what the Jags did in signing Calais Campbell and AJ Bouye to huge deals in FA or the Browns signing Landry to top-of-the-market deal (for a slot wr) and making the trade for a star like Odell.
It's simple the owners don't care about winning and won't sell the team (it's a show of legacy and status for them). Bengals useless and unless Burrows becomes an HOF QB, they're not making it to the superbowl, as result.