Just a few notes:

 Yea, you see it (maybe not in-GAME tho ha haaaa...), it's hands down BiS. It's VERY hard to come by considering it doesn't drop from Midtown Gobbo for whatever godforsaken reason; only Bugle and maayybe Doom terminal (there's conflicting info about the latter). I dropped SAW BEFORE I found this as a cosmic and I'm not alone in that regard. I know the title is "DEFINITIVE" in all-caps but ultimately "BiS" =/= "required". At least in some cases....  IS actually required for this build's power rotation to function properly unfortunately :/ 

I go back and forth between  and  for the final artifact slot. Siege is probably higher damage overall, but it won't be consistent on a build that has only one single itemslot with power duration like this. 

 is better than Attilan I know... just like it is on almost every other character. As a functionally full area-tagged build, movement Spidey can run  and free up your Atlantis stacks for the other ~60 heroes on your account :) 

  is better than Spidey's own  but it's close. If you've had rotten luck when it comes to CHT drops, or   giving you garbage like me :)))) you can use his personal slot 4 and not feel too bad about it. Especially considering Spidey isn't a power duration merchant like a lot of the other heroes who have Skrull uniform as their BiS.

On the insignia: The generic recommendation, especially for characters with no auto crits/bruts, is crit damage/rate... but again, movement Spidey is a ~100% area tagged hero getting a big chunk of effectively unconditional crit rate from    along with occasional guaranteed crits from the   . Uniquely positioning him to take good advantage of area damage on insignia, which unlike brutal damage for example (which rolls prohibitively poorly for its stat weight here) rolls pretty generously up to 500; higher than melee, ranged, and boss damage in the same slot by 100 points or more. Crit and Brutal strike are still good of course, use whatever you happen to have that's rolled the highest. Note: itembase is bugged and doesn't correctly list all of Spider-Man's team insignia affiliations as they are in-game. Everything except Defenders, Thunderbolts, and Inhumans insignias are usable on him, so despite what I have shown in the build I'd actually recommend Cyclops Insignia as the "best" choice if you're lucky enough to find a good one. 

On vulnerability: Spidey is in the awkward position of possessing a crap vulnerability power   that should actively be avoided outside of levelling, not scaling on either mainstat found on , and being outright unable to equip Anti-Metal ammunition (which hilariously would be a fine placeholder for  on him if he WAS a "gun hero"). Meaning you will have to lease his vulnerability application out to either your teamup hero, one of your artifact slots, or other players in group content. Your best and most reliable choice will be to just put the   in the bag with a 10% sig CD cosmic affix on top. Relying on a teamup as your sole avenue of vulnerability upkeep is generally NOT recommended in practical gameplay for a variety of obvious reasons. But if you do choose to go this route... your best option is:   followed by either of . The vulnerability power from  is decidedly worse than the aforementioned three, having a noticably lower duration than its cooldown (among other issues) and as such is terminal levels of cope/not viable. If you're only ever going to play in patrol zones or raids with other people, you can be "that guy" and just not run a vulnerability source of your own at all as you mooch it off of others. But of course that's a non-starter if you're ever on your own... so try not to be "that guy" if you can help it.

On the Infinity System: Most movement tagged abilities in Marvel Heroes BUE don't benefit at all from attack speed! Making the oft recommended ~37 points in Temporal Loophole a trap on builds like this. If you have absolutely zero issues with survivability on Spider-Man you can forgo the points in Gravity Well and proceed to dumping points into more Fighting that much sooner. But keep in mind that despite the fact that he's moving around constantly... most of the movement in this build is long-winded jumping animations (that can't be sped up by stacking ATK speed as you know) with zero I-Frames or damage resistance, that position Spidey right into enemy melee range. So he isn't nearly as "evasive" in practice as one might hope; I personally always invest the 150 points into increasing base HP as it makes him much more comfortable to play. Spidey also has full 100% weaken uptime as long as you're ragebaiting with  off cooldown, so don't forget about the Show of Force node in Power Gem if you're in the big boy leagues of 1K+ IP but are waiting for the full 25 necessary for another bit of Fighting. Oh, and 0.6% chance in the critical and brutal strike chance nodes rounds up to a full 1% due to a glitch, in case you were wondering about that. :)