The comparison to Marty Jannetty I'm not sure I get... the only thing similar between Marty and Christian is that they were both the second fiddle in their tag team, but Christians success as a singles wrestler is miles beyond Marty's.
So if you are asking "who was the greatest tag team star to break off as a singles star but be the lesser member of their tag team"? Then maybe.
This is the misconception. Jannetty was NEVER the weaker of the two Rockers, in fact he was very much portrayed as the more experienced captain of the team, more likely to succeed in the long term. Two things hurt him badly to turn his career.
The Charles Austin incident, where Marty was deemed to have broken a jobbers neck with the Rocker Dropper (despite the botch being with Austin taking a flip rather than a faceplant) was clearly an accident, but it cost WWE huge money ($26.7m) although the judgement wasn't settled till a few years later, after...
Shawn made his first "screwjob" by blatantly lying to Vince about events around their Royal Rumble match in 93. The match had gone down a storm on the circuit but Vince had decided for the PPV to throw Sherri, in and radically alter the dynamic. Janetty clearly hurt his shoulder during the match, Heenan even commenting you could see the bump where it had potentially dislocated. Vince was disappointed in the pair of them but kind of understood that Janetty had been hurt, until Shawn got in his ear and said Marty had been partying all night and was still drunk.
Vince immediately fired Jannetty... which many saw as harsh, and he didn't take it well, starting his cycle of partying. The saving grace came via an unlikely source, Curt Hennig heard of what had occured and Shawn admitted he had lied. Perfect went straight to Vince and told him, and Marty was given one of the few "Billy Martin's" in WWE History (for those who don't know being reinistated as if nothing had happened, with a bonus for inconvenience) and got his IC reign in that famous return... Was Marty mad, sure, did he potato Shawn a bit, sure... but it again made for a great segment and started Marty's IC reign off strong.
Sadly, by then he was into his self destruct mode mainly out of guilt over the Austin thing and when the judgement came in the plug was pulled quickly - he was given more chances but he couldn't live up to it... When the Rocker's finally reunited during Shawn's feud with Kurt Angle, there was talk of them (from Shawn of all people, who looked like he had the best time he had had in years during that match) making a run of it, and Marty was clearly in good shape and over... but for whatever reason they didn't go there and his trainer job was also quickly rescinded...He was consigned to this insulting thing where people say "The Marty Jannetty of a team".
The guy had the IC title and the Tag titles post Rockers, more than the team had.
Christian is not a "Marty Jannetty of the team", nor was Marty Jannetty, who had a respectable, short mid card career and several stints as a lower midcard/opener. That's more than a Koko B. Ware and more than Rocky Johnson, Tony Atlast, Tony Garea, Jim Duggan or Jimmy Snuka achieved for the HOF.
Christian was always a top talent, who spent some time after the split of E&C building momentum in the mid-card, he was always pushed, always given tag and IC titles and most importantly, patient. When Vince balking at pulling the trigger on a main event push against Cena coincided with his contract expiring, he did the extra couple of nights required to end his storyline rather than the Lex Luger path to TNA. When he went to TNA and was given that push, he didn't waste it or get in trouble backstage, he was professional, raised his and TNA's profile and then was welcomed back to the E in a role to reflect his achievements.
Had Edge not had to retire, would he have gotten the World title? Probably not or if so it would have been a short reign, but he didn't get it as an Edge "replacement", the "Shawn of the team's" retirement simply opened up a spot that he was in line to take due to his hard work and popularity.
You don't here about Jay Reso getting DUI's or divorcing/having affairs or other things that bring WWE into disrepute... he even went to a TNA show he didn't want to go to cos it helped the E get Flair back for a night. He took one for the team... you hear that he's a well loved guy by the fans and locker room, does the job without complaints but is ready to step up and steal the show whenever he gets the chance. For Janetty you also hear that about him, but he had his demons and he couldn't beat them. That's stil a Hall Of Famer through and through however... Janetty could have been what Christian had a couple of bad things not gone wrong right at the start.
If you want to use tag wrestlers who never lived up to the hype then say the "Tony Atlas" of the Soul Patrol, the Brutus of the Dream Team or the Crush of Demolition... the're all FAR more accurate than using Jannetty and comparing Christian to any of those guys is downright offensive.