So with FastJack having vanished, do you think it would be a reasonable assumption to say that Dodger is now the world's most skilled hacker?
No. Nor, in fact, would I place Fastjack as being the world's most skilled hacker. In part, it's a matter of how the skills work, not just the theme.
Skillwise, Jack clearly had a 13 in one of his decking skills, but the question is 'which one?' What was he most famous for? IMO, he was most famous for being the toughest SOB you'd ever want to meet in cybercombat, so his Aptitude goes there. Dodger might be in the 10-12 range on one or two of the skills, but though being good at sneaking around (per se), after Morgan came around he was simply never really dedicated to the job - he was dedicated to
her. I'd honestly put Dodger at 8-9, because when it started out, he had Morgan/Megaera doing half the work for him, and afterwards he made deals to open the doors and permit him to hunt.
Thematically, it's two-pronged - on one hand, you can't be the best at everything (and hacking has a whole handful of 'everythings' to be best at), and on the other hand, it's an 'any given Sunday' proposition. When you've got the two best facing off, the skill difference is going to be miniscule, and luck - where you are, what the local IC is doing, how much signal noise or delay you happen to be dealing with, etc. etc. - enters into it far more than either of the two of you would like. Fastjack was great, sure, but when he goes up against (it pains me to write this) Michael Sutherland in Wuxing's area, who's going to lose? Fastjack, because Wuxing is Sutherland's home ground. What if the test isn't combat, but information acquisition?
One wouldn't ask 'Who's the best street sam', because of similar reasons: best at what? Fastest, most durable, can go the longest, best shot with an [Insert Weapon Here]?? Fastjack has a claim, but like Kane he definitely has the fame - which, IMO, means that those people who work their asses off to be both fantastic at their job AND quiet at it wind up getting the shaft in 'who's best' popularity contests, but will probably wipe the floor with the well-known guy when it comes down to brass tacks.