Was better: Samoa Joe

Without a doubt, WWE have still not used Samoa Joe to his full capabilities. He is now a part of the Monday Night RAW commentary and should return to the ring soon.
As for his in-ring performances, he will be fondly remembered by the fans for his time at TNA and ROH. Joe was one of the key figures at TNA and put them on the map but a move to WWE saw his reign as the top star in NXT. It may be a little early to pass a judgment on Joe's WWE career, but as things stand, TNA is still the place where he reached his peak.
Became better: Triple H

The rise of Triple H has been one of the best the world has ever seen. He was very good in the ring at WCW but a move to WWE saw him take his performances to another level.
Vince McMahon put a lot of trust in his and The Game revealed that the WWE Chairman himself offered him the deal to move to the company. Triple H has held the WWE Championship nine times while also becoming the Heavyweight Champion five times in his career. Adding to that, he also won the Royal Rumble twice and the King of the Ring tournament once.
Becky Lynch has been challenged HERE.