Razorend is a good weapon, for sure, but in terms of crit profile it's not even in the conversation:

Razorend: 13-20x3
Brush Hook: 12-20x4

There's also handaxes, which can get +1 crit multiplier from kensei ML6 core and +2 range (+4 w/imp. crit) from swashbuckler, which is a nice combo. Assuming another +1 range from Divine Crusader:

Forgotten Axe: 13-20x4
Unseen Blow: 14-20x5

The problem with Unseen Blow is that there's only the ML14 heroic version, so it's not great for epics.

My take on PDK is Fighter/Cleric/Monk, nets you 15-18/x4 19-20/x7 in LD. If you use a Drow Maul you're up to 13-18/x4 19-20/x7 which is better than a 12-18/x4 19-20/x5 of EllisDee37's Swashbuckler Brushhook (assuming Overwhelming Crit which wasn't listed).
Also you get some pretty awesome melee power along the way. But that's for another post.

20/x3 Base maul (Drow Maul is just +2 range)
19-20/x3 ICrit
17-20/x3 Silvanus
16-20/x4 Kensei Core 3 Tier 5
15-20/x4 LD Pulverizer
13-20/x4 Drow Maul

19-20 +1 Overwhelming Crit
19-20 +1 LD Devastating Crit
19-20 +1 Greater Sun Stance

(11*1+6*4+2*7)/20 = 2.45 assuming miss on a 1

For comparison Brushhooks 12-18/x4 19-20/x5

(10*1+7*4+2*5)/20 = 2.40 assuming miss on a 1

Although technically the best I've found would be a Barbarian/Fighter/Cleric Silvanus build. Doesn't have great synergy outside of crits, but oh boy they're friendly.
Ravager T5 obv doesn't stack with Kensei T5, but it's +2 when raging so:

20/x3 Base maul (Drow Maul is just +2 range)
19-20/x3 ICrit
17-20/x3 Silvanus
17-20/x4 Kensei Core 3
15-20/x4 Ravager Tier 5
14-20/x4 LD Pulverizer
12-20/x4 Drow Maul

19-20 +1 Overwhelming Crit
19-20 +1 LD Devastating Crit

(10*1+7*4+2*6)/20 = 2.50 assuming miss on a 1

End result it might actually be the best baseline (obviously Swashbuckler Exploit Weakness wins if you're counting averages).

It's also nice because you can run in LD instead of having to run in DC.

Ok; so my list so far looks something like this:

Barb/fighter/cleric sylvannis; LD; with drow maul of the weapon master: 2.50 (12-18 x4, 19-20 x6)
Bard/fighter in DC with Axe of the Unseen blow: 2.45 (14-18 x5, 19-20 x6)
Barb/fighter in DC with Deathnip: 2.45 (14-18 x5, 19-20 x6)
Assassin in DC with Assassin's Kiss (or other named): 2.45 (14-18 x5, 19-20 x6)
Fighter/Cleric/Monk Sylvannis; LD; with Drow Maul of the Weaponmaster: 2.40 (13-18 x4, 19-20 x7)
Swashbuckler in DC with Brushhooks: 2.40 (12-18 x4, 19-20 x5)

And as a reference point; here's where a Khopesh dual-wielding build might sit at.
Paladin in DC with Khopesh of the Weaponmaster: 2.30 (13-18 x4, 19-20 x5)

In one of the Silvanus threads, someone complained that drow maul in LD wasn't getting its full crit range bonus, suggesting that something wasn't stacking like it should. I don't have an epic Silvanus build w/drow maul I can use to test that, though.
Bard/fighter in DC with Axe of the Unseen blow: 2.45 (14-18 x5, 19-20 x6)
Barb/fighter in DC with Deathnip: 2.45 (14-18 x5, 19-20 x6)
The downside to these two is that they're heroic weapons, ofc, with no epic named options which are quite as good. But since OP asked about best crit profile not best DPS...
Assassin in DC with Assassin's Kiss (or other named): 2.45 (14-18 x5, 19-20 x6)
Good catch: I forgot that Assassin's Kiss is the only dagger with x3 crit multiplier.

EDIT: Forgot to include any ranged weapons. Gt xbows with Expert Builder + Celestial Champion become 14-18/x4 19-20/x5. Needle with Keen Edge + Strike w/No Thought (or Expert Builder + gnome crit range bonus) is 15-18/x4 19-20/x5 in DC. Likewise a pure rgr or Kensei can hit 15-18/x4 19-20/x5 in DC with Pinion or Sapphire Sting.

I can confirm that as of some previous (but recent) lives - there's some combination that just doesn't work properly.  DC + Silvanus can be weird too.  I think a couple of the ranges are typed the same behind the scenes.

I don't remember, to be honest.  Gave up after it was released broken, and they were like "yeah, we know" for YEARS.  It was on the known issues list less than a year ago.

Test it - maybe they fixed it.  Keep in mind it'll display like it's working, but the combat log shows it isn't.

As long as your ammo is limited by the number of things you've killed.     Books, ok, ignoring the logistics of carrying them all around... where the hell do you get a ready supply of ghosts?!

shout out to my nigga Grand. At least he was using those socks for good trying to get bugs fixed.

Are you serious, he was Grand? Wow, shows what you miss if you don't keep up with vault drama. Color me impressed, dude pulled off the act expertly.

He singlehandedly gangraped Ash so hard, dude's got a cross between a sock fetish and phobia now.

Handaxes are my melee weapon of choice because of the fighter/bard split mechanics.