The Toffees had stolen the show so far in this summer's transfer window recruiting a plethora of talent including Wayne Rooney, Michael Keane, Onyekuru, Davy Klassen, Jordan Pickford, Sandro Ramirez and Josh Bowler.
Since Romelu Lukaku's record-breaking move to Manchester United, Koeman has been linked with moves for target men like Olivier Giroud and Soloman Rondon and reports suggest their business is far from done.
Ronald Koeman was widely regarded to have done some of the best business across Europe.
New manager Ronald Koeman
But has Slaven Bilic stolen his thunder with a wonderful week of recruitment and reports of more to follow.
The Hammers were one of the first to do business this summer with the shrewd free transfer signing of experienced defender Pablo Zabaleta from Manchester City, solving their problem right back position.
But nearly two months passed since his arrival with no further recruits and the club's fans were not happy.
It didn't help that Koeman stole Onyekuru from under West Ham's nose and there were even growing calls for David Sullivan and David Gold to sell up to more ambitious owners.
But a stellar week has seen the East Londoners bring in Joe Hart, Marko Arnautovic and Javier Hernandez with speculation that they are not done yet either.
Javier Hernandez looks to be one of the signings of the summer
The likes of Keita Balde Diao and Jack Wilshere are other names being heavily linked with the London Stadium while Everton find themselves running out of options to replace Lukaku.
But who has done the best business? You decide...