The Red Devils allowed the France international leave Old Trafford as a free agent and join Juventus in 2012. He developed into a world class player at the Turin club and his form for both the club and country saw him attract a lot of interest from top clubs across Europe.
Jose Mourinho's side then successfully landed the midfielder as United re-signed Pogba for a world-record fee of £89 million earlier in August. The midfielder has failed to impress so far for the 20-time English champions and is yet to showcase his true worth in the Premier League.
Henderson, on the other hand, has been shining under Jurgen Klopp and has scored and assisted one goal in seven league matches this season. His league goal was a stunner against Chelsea as the Reds sealed a 2-1 win over Antonio Conte's men.
Merson says things could change going forward, but considering the current form, he believes the England international is way ahead of Pogba.
"Today, Jordan Henderson," Merson told Sky Sports. "Over the next 10 years, I don't know - it probably should be Pogba considering how much money they spent. Henderson has been as good as anybody in the Premier League. Credit where credit is due, he's been outstanding. Pogba has been struggling."
What Merson is claiming will be found out when Jurgen Klopp's Liverpool will host United in the Premier League clash scheduled between these two sides at Anfield on Monday evening. Pogba has showcased his qualities while in action for Juventus and also for his national side.
Henderson has also been impressive, but the current comparison is unlikely to be accepted by the Old Trafford faithful. Another struggling player at United is their captain Wayne Rooney. The England international was left on the bench by Jose Mourinho in the last three fixtures.
I would play Rooney against Liverpool: Merson
Merson believes Rooney's absence from No 10 position will put further pressure on Pogba and has advised the former Real Madrid and Chelsea manager to start his captain and bench Jesse Lingard for the clash against the Merseyside club.
"I would play Rooney in this game. Jesse Lingard has just played two international football matches - that can be very draining. He's a young lad. If you put Rooney in this game it would take a lot of pressure off Pogba," the Sky Sports pundit explained.
"If Rooney's on the bench, then all eyes are on Pogba. For all that money, he hasn't performed yet. He's been nowhere near any good. If Manchester United lose, then he'll come in for some big criticism."