Blue
Ravenous Bugblatter Beast of Traal
Easy, a rogue. A fighter. Barbarian. Heck, a ranger with the right feats.5th level paladin using a greatsword. 10STR No feats or shenanigans, just class features and smites.
Two attacks.
With super double crit luck: 8d6+12d8 radiant (rerolling 1s and 2s)
With Crit and a hit: 6d6+9d8 (reroll 1, 2)
With Crit: 4d6 + 6d8 (reroll 1, 2)
With hit: 2d6 + 3d8 (reroll 1, 2)
Of the multiple scenarios 0, 20, 41, 61, or 82 damage (not factoring in the 1,2 reroll).
Show me another 5th level character that could come close to these numbers using just class abilities.
Because you are asking the wrong question. The way you are asking the question masks that you are using up a limited resource.
It is also looking at the corner case of not just a crit where beign able to apply to that does more, but to double crits. 1 in 400 is not, ever, a good indication of general play.
Now, run 6 encounters in a day. Total up your damage from your smite and non-smite attacks. Compare to totals from other classes. The at-will rogue will have a very consistent expected output - and crits will also double their 3d6 SA. Not as many dice, but happens in a heck of a lot more rounds of the day then a paladin smiting.