The latter part of the 90s saw both WWE and WCW engaging in a rating war that lasted for several years. The two corporations were hell-bent on trumping each other at any cost, and it gave birth to possibly the greatest era in the history of professional wrestling, the Attitude Era.
By early 2001, WCW's product had become watered down and the ratings had fallen to the point that Vince McMahon managed to buy his competition off in one of the most memorable moments in all of pro-wrestling.
Over the next few years, Vince McMahon brought in a bunch of WCW stars, in addition to the ones who had jumped ship to WWE before WCW's ship sank. A select few managed to impress the WWE Chairman, while many others weren't pushed to the main event throughout their WWE stints.
Let's take a look at five WCW stars Vince McMahon pushed in WWE, as well as five stars who he didn't.
#5 Chris Jericho (pushed)

The current AEW star made his way to WWE way before WCW was bought off by Vince McMahon. The decision was a right one on Jericho's part, as he turned from a WCW Cruiserweight to one of the greatest World Champions in WWE history.
Jericho feuded with all-time greats like Shawn Michaels, John Cena, and Triple H, and is a nine-time Intercontinental Champion. His star is still shining bright all these years later, and he is currently doing his bit towards turning AEW into a top company and an alternative to WWE.
#5 Buff Bagwell (not pushed)

Buff Bagwell was a strong mid-carder in WCW and won the WCW World Tag Team titles on 5 occasions. When WCW was bought off by WWE in March 2001, Bagwell was one of the first wrestlers to sign with Vince McMahon's promotion.
He soon faced Booker T for the WCW title on an episode of RAW in his debut match. The bout left a lot to be desired and he was released mere days later due to complaints about his demeanor.
#4 Eddie Guerrero (pushed)

Eddie Guerrero was another WCW Cruiserweight whose potential on the mic as well as inside the squared circle was recognized by Vince McMahon. He spent the majority of his early years as a mid-carder but was finally given his shot at glory in early 2004.
Guerrero not only defeated Brock Lesnar for the WWE title, he successfully defended it at WrestleMania 20 against Kurt Angle. By this time, he had become one of the most beloved Superstars in WWE, thanks to his hilarious antics and his motto of lying, cheating, and stealing that he so effectively utilized in his matches.
#4 Dean Malenko (not pushed)

Malenko first appeared on WWE TV in January 2000 along with Chris Benoit, Eddie Guerrero, and Perry Saturn, with the quartet dubbing themselves The Radicalz. While Eddie and Benoit soon became top Superstars and won World titles, the other two didn't do much of note during their brief main roster stints.
Malenko did win the Light Heavyweight title on two occasions, but that was the extent of his WWE accomplishments as a wrestler. Malenko quietly disappeared off WWE TV before the Invasion storyline kicked off in summer 2001.
#3 Rey Mysterio (pushed)

Rey Mysterio was a 5-time WCW Cruiserweight Champion who made his way to WWE in 2002. He immediately turned into a fan favorite and was featured on SmackDown's Cruiserweight division for years on end, winning the title on three occasions.
Mysterio won the 2006 Royal Rumble match that he had dedicated to Eddie Guerrero, who had tragically passed away in November 2005. At WrestleMania 22, Mysterio defeated Kurt Angle and Randy Orton in a Triple Threat match to win the World title. Mysterio won the top prize on three occasions during his WWE stint.
#3 DDP (not pushed)

Diamond Dallas Page's WWE run ended up baffling a lot of fans, as he was a three-time WCW World Champion and one of the biggest stars in Ted Turner's company. He debuted in WWE soon after WCW was purchased, and was revealed as the stalker of The Undertaker's wife, Sara. DDP won the European title once, in addition to a Tag Team title run with Chris Kanyon. but he didn't replicate the success he had in WCW.
On an episode of SmackDown in 2002, he suffered a serious neck injury during his match with Hardcore Holly. DDP announced his retirement in June 2002 after consulting multiple doctors, although he did make his return to in-ring action on the independent circuit in 2004.
#2 Goldberg (pushed)

Possibly the most exciting WCW star during the Monday Night Wars, Goldberg made his way to WWE immediately after WrestleMania 19. He soon bagged the World title and held it for the next few months before dropping it to Triple H. Goldberg then went on to defeat Brock Lesnar at WrestleMania 20.
He came back to WWE in 2016 and had a bunch of short stints that saw him winning the Universal title on two occasions. Goldberg was inducted into the WWE Hall of Fame in 2018.
#2 Scott Steiner (not pushed)

After leaving the company back in mid-1994, Scott Steiner made a grand return to WWE at Survivor Series 2002, attacking Matt Hardy and Christopher Nowinski in the process. He soon got into a feud with Triple H and went on to lose the feud at No Way Out 2003. His two World title matches with Triple H have been deemed by many as two of the worst bouts of 2003.
Steiner later formed an alliance with Test, but the duo never bagged the World Tag Team titles. He suffered an injury in mid-2004 that sidelined him for a couple of months. WWE released Steiner in the midst of his injury, marking the end of a forgettable run.
#1 Triple H (pushed)

After a forgettable stint in WCW in the mid-90s, Triple H signed a contract with WWE. He was squashed by The Ultimate Warrior at WrestleMania 12 but things were only going to go uphill from that point on. Triple H went on to become one of the greatest Superstars in WWE history.
He has headlined several WrestleMania events, won the World title on 14 occasions, and has led legendary stables like Evolution and DX. The Game has done it all inside the squared circle and is currently nurturing the Superstars of tomorrow in WWE NXT.
#1 Sting (not pushed)

Sting was the biggest WCW star who had never signed with WWE. It all changed in late 2014 when Sting appeared at Survivor Series 2014 and helped Team Cena defeat The Authority in the main event of the show. Many were hoping that Sting's arrival would lead to a dream match with The Undertaker, but we got Sting vs Triple H at WrestleMania instead, which The Game eventually won.
Sting later got into a short World title program with Seth Rollins and the feud ended at Night of Champions where Rollins emerged victorious. Many fans have wondered whether Sting would have been pushed and given a bunch of World title reigns if he had signed with WWE earlier. He was arguably the biggest babyface in WCW history and it's a shame that the WWE Universe didn't get to see him wrestle in WWE in his prime.