This is a really tough question to be honest. I'm a believer that you have to look at the players career as a whole, the era they played in, how they played in the clutch, etc...
I have to admit, the last couple years, I've honestly thought to myself that Lynch might be the best in his era. It goes well beyond statistics with him. People compare Kobe to Jordan all the time, and while the stats are in Jordan's favor, they don't compare at all if you really watched basketball. You'd be a damn fool to pick Kobe on a team over Jordan if you could do it all over.
Lynch is incredible. That last drive last week kinda said it all. You desperately need a touchdown, and the clock is running out. Very few teams are going to hand the ball off on that drive. If I remember right, they gave the ball to Lynch twice, both for huge plays. One was a big time first down, the next was a 27 yard touchdown and grabbed his nuts in the end zone. That was it. He doesn't seem very motivated, and seems super weird off the field, but he's flat out incredible at running the ball. Not to mention, he damn near scored on that catch the drive before in another incredible play. If I have to hand the ball off to anyone in this era of running backs, I'd want it to be him. He's way better than Murray IMO, and way more durable. Murray is good, I've seen him play since he was at OU, but he was a steal in the draft after all was said and done because he wasn't a highly touted recruit. They have what might be the best line in the league and a formidable passing attack, of course he's going to shine there.
As far as all time? That depends how you're rating him. I know this doesn't make a ton of sense, but Barry Sanders is the all time greatest RB IMO. But I think Payton is the all time greatest player. Payton could do things that Barry Couldn't, and if I was building a team, I'd want him over Barry. But as far as running the ball, no one was better than Barry. But if you need a couple yards in a crucial part of the game, I'd rather hand it to Payton. If you need a critical block on a passing play, I'd rather have Payton. If you need a dude to catch a pass out of the backfield, I'd rather throw it to Payton even though Barry was better in the open field after the catch. Barry was almost never given the ball <5 yards in. I think he would've done better than they allowed him to be, but multiple coaches followed that plan of attack, not sure why? Maybe it's his tendency to lose yards at times? But either way, he's the best RB to me and would've killed the record if he kept playing. I think his dad was always in his ear telling him that Jim Brown was better. He played 10 years and quit and always talked about that. I wonder if that had something to do with it? Barry played 9 and was really only 1 season away from passing Payton on the all time list.
Sanders also had some pretty good teams in there, and had the luxury of playing indoors. People always talk about how bad his teams were, they weren't that bad. He's my favorite player all time and I followed his career closely. They were especially good when Herman Moore was at his peak and Johnny Morton was there. Scott Mitchell either lit it up or threw 5 picks a game. Barry was beastin around that time too, probably as a result of the passing attack as well.
All time, I'd say Sanders, Payton, Brown and from there it gets tough. Gotta add Faulk, Tomlinson, Dickerson, Simpson, Smith in there, then maybe Bettis, then Peterson and Lynch. So maybe Lynch is like 8-10 all time as it stands? People act like Peterson isn't a beast right now still even though he missed last year. He ran for more yards in one season than Barry on a terrible team.