Since this question has been mentioned once or twice in public since KC claimed Robes is a better hooker than he ever was I figure it's time to really get into the meat of this debate.

What skills, attributes, qualities, achievements, stats, awards etc. best sum up both players? And if it is possible to rank one over the other - precisely why?

I'll take a brief stab at the most obvious strengths but will wait to see what others say before I try to work out who was better.

I'll start with Cunningham:

One of those rare physical freaks who seem to skip the years between adolescence and full maturity.
Required almost no "settling in" period following his debut age 17/18 and never looked back.
Low of gravity coupled with explosive power, enormous leg-strength and a jack-hammer handoff which wasn't far behind.
Poacher's nose for tries - and scored a staggering 175. Practically unstoppable near the line.
Whilst rarely mentioned there were few who tackled consistently with better technique and harder. Hit like a pile-driver.
Mentally rock solid. Hardly ever recall him flustered. Didn't give away penalties. Never lost his temper (aside from that one time when Tomkins attempted to attack his injured standing leg). Never seemed to give in (as evidenced by the Mark Smith tackle or the match-winner at Warrington).
At the top of his game for 10+(?) years before suffering the only major injury of his career.
Unquestionably the best hooker in the competition judged over his career.
Immortalized in bronze.

The one thing Cunningham did that roby doesn't is hit hard, very hard. it was like having a 3rd prop in defence. Roby counters that with his engine.
I rewatched the wire game and he was everywhere. not only was his tackle count high, but he was so often leading the kick chase, which is vitally important.

Both started as runners and developed their distribution/playmaking game as their career went on. For me, I think Roby's is better, plus he's got the kicking game.

Keiron also had something that Roby's never had - James Roby (and before him Micky Higham). Robes is an 80 minute player, doesn't take a rest, doesn't get to come back on fresh to run at tired defenders.

I think Roby might be the most complete player we'll ever see and I think that 90% of the time he edges KC, but I do think Cunningham had a little extra magic tucked away.

Cunningham lost his temper with Lee Penny when he high tackle Alan Hunte in Superleague 96. Penny had been sent of at KR in the final winter season for a punch on Cunningham.

Thinking about comparing these two makes my head hurt. We have been truly blessed for the last 20 years.

Didn't Lee Briers greb on KC once? I've a vague memory of him going ballistic about that.

'Greb' ... I think I was in short trousers last time I used that word.

Cunningham revolutionised the hooking role. People suggest he prospered solely off quick ball but quick ball was common prior to his career and I don't recall too many doing what he did. He alone was responsible for the hugely vital attacking strike weapon a hooker has become. He was the start of it.

His defence was not just good but impactful as well. In a manner that Roby's simply is not. Roby may make a lot of tackles but in a game where a big prop is chewing up yardage on us, how often have you seen Roby pick him out and hammer him ? Not once. Cunningham used to do it constantly. He'd change games in attack and he'd change games in defence.

Cunningham also demonstrated an ability to change his game and still be world class. Post injuries, he developed a passing game that Roby still cannot match. Teams were that scared of him going from dummy half that the flat ball across a defence always led to a walk in try, usually for a prop forward.

I love Roby. His engine, work rate and effort levels are brilliant but I'm sorry, Keiron Cunningham he simply is not. Cunningham set the benchmark and was the very best. Roby works his backside off but even at such incredible effort levels, is still not able to match Cunningham's impact, defence or passing game. That's before you even discuss the running from dummy half where as good as Roby is, he ain't no Cunningham.

Keiron defined matches. He won them on his own. He stood up and did something required when the walls were breaking. Roby when we're under the pump I feel goes missing somewhat - Cunningham was the opposite. I'd guess if you asked any opponent of ours whom they'd rather was facing them in the 9 shirt, I'd bet they'd all to a man pick Roby.

I agree with most of what you say, but not this. I think Robe's service is as good as KC's ever was.

We agreed about KC hitting harder, but that doesn't mean Roby's defence can't swing games in its own manner. For instance, the way he's often leading the kick chase is of massive influence on the team and if its resulting in the catcher getting tackled in his own 22 of t least pinned back by their try line.

As I say, KC would perhaps be more likely to pull out that magic play, which is what people like to remember, but overall effect on the match, I'm still leaning toward The Robot.

I think I would go for the "The King" Cunningham over "The Dynamo" Roby, KC was better passing off the floor from the PTB and had better vision of the game to put added pressure on the opposition. Roby is world class in finding open play and had a better kicking game.
KC had scored over 175 tries and probably had a better offloading game than Roby, I,m sure KC was voted in the rugby press The Greatest Player of the Superleague Era (1996-2007) when there were probably more quality players around that period.
Roby may possibly be the last great hooker in a Saints side as the quality of players start to degenerate. We need to look after him for the next 2 years until hopefully someone else comes along.

Its tough to choose and you guys really have been blessed with 2 all time greats one after the other almost.

Imo though i would say Roby has been arguably a more important player for you over the two decades simply because he has had to act as stabiliser to all the greats you had retiring and moving on.Cunningham had the likes of Long,Sculthorpe,Martyn,Pryce,Joynt,Lyon,Wellens (in his pomp) hell he even had the young Roby to act as his interchange when he was in his youth.In comparison Roby has been the one true World class player you have had this last few years of your transition and he always seems to be playing at the top of his game.In Cunningham's day, if he was missing,its fair to say you would still have been contesting top end and for trophies, In this era without Roby you most likely would not have, so he edges it for me.

You won't find me saying a negative thing about Roby. He's a superb RL player.

However, the simple truth is that the only core skill he betters Cunningham at is kicking. Roby is an effort player and he surpasses all at it. Cunningham was that and more. He was a difference maker. He won games.

I genuinely think Roby's efforts have made people forget just how good Cunningham was. From the day he set foot on the rugby field, he was the best.

I love Roby, but Cunningham was the King.

I guess that's a massive compliment in itself. I often think that about Jamie Lyon and Paul Newlove.