math me please!

[Occasional Sage]

Rogue1 for Expertise:Athletics, Champion3+ for 19-20 crits, halforc for Savage Attacker, Shield Master for bonus action shoving prone to gain Advantage.

Given that, what's the best weapon? d6 Finesse to activate Sneak Attack, or d8?

[AvatarVecna]

Rogue1 for Expertise:Athletics, Champion3+ for 19-20 crits, halforc for Savage Attacker, Shield Master for bonus action shoving prone to gain Advantage.

Given that, what's the best weapon? d6 Finesse to activate Sneak Attack, or d8?

At the risk of sounding like an ******* for pointing out something that seems obvious to me, why not use a rapier, a d8 Finesse weapon? I mean, even if that wasn't an option, though, it'd be difficult to decide which weapon was better without knowing your Str or Dex.

[Rysto]

Why not go with a Rapier for d8 Finesse and get both?

[MrStabby]

How many attacks are you looking at and with what frequency do you expect to get opportunity attacks? Also vs which AC, roughly?

[Occasional Sage]

Oh. Duh. Clearly, time to sleep.

[imaginary]

Don't you need Str for Shield Master?

[Rysto]

You can use Str with a Rapier. The condition for sneak attack is a finesse weapon*, but it doesn't say that you have to attack with Dex.

* Or a ranged weapon

[CaptainSarathai]

Don't you need Str for Shield Master?
Not really. SM doesn't have any prerequisites, and Shove is actually a contested Str(Ath) vs Str(Ath) or Dex(Acro) check.
Having the Expertise means that while he does need a little Strength, he doesn't need as much. It's actually a pretty good combo for a Rogue to get his boosted damage.
The problem is that you must take the Attack action to trigger SM. So the argument can be made that you do the shove last, so the target won't be prone during your attack action (although, you can always use an attack to shove, rather than making a weapon attack)

[Occasional Sage]

Not really. SM doesn't have any prerequisites, and Shove is actually a contested Str(Ath) vs Str(Ath) or Dex(Acro) check.
Having the Expertise means that while he does need a little Strength, he doesn't need as much. It's actually a pretty good combo for a Rogue to get his boosted damage.
The problem is that you must take the Attack action to trigger SM. So the argument can be made that you do the shove last, so the target won't be prone during your attack action (although, you can always use an attack to shove, rather than making a weapon attack)

That's not a problem if you read the rules. A Bonus can be taken before or after your Action, so the sequence would be:

declare the Attack action
shove as a Bonus via SM, triggered by attacking
attack with Advantage