Conflicting numbers from different calculators; which one is right?

I just smacked my Wyeast 1388 Belgian Strong Ale and am now planning for the starter later this afternoon. I'm brewing the Belgian Strong Golden Ale from NB. Typically, I use Beersmith 2 but have been digging around as I sometimes question Beersmith's numbers. Can you guys have a look at the numbers below and give me some feedback please. Let me know if you need more info and as always, thanks for the input.

Recipe:
OG: 1.080
Batch Size: 5.25 gal
Type: extract
Yeast: Wyeast 1388 Belgian Strong Ale (manufactured 2/28/2013)
Stir plate: Yes

Beersmith:
Yeast Cells Needed: 273.7 Billion
Starter Size: 1.2 liters
Yield: 273.7 Billion
Yeast Viability: 96%

Mr. Malty
Yeast Cells Needed: 287 Billion
Starter Size: 2.57 liters
Yield: info not given
Yeast Viability: 71%

As you can see the starter sizes are quite different as are the needed cell count and viability. Who is correct?

Beersmith 2 seems to be the leading software but as mentioned, I sometimes a question the numbers. How accurate is it?

 

Check your viability numbers. Beersmith looks to be giving you the starter volume based on 96% viability. Mr Malty is going off 71%.

In mr malty, there is a viability calculator when you input the date. Wyeast uses a packaged date if memory serves. Input that date into the calculator and it will make the viability calculation and suggest your starter size from there

If you use a white labs yeast, they give a "best by" date, which is, and someone here correct me if I am wrong, 4 months after the package date. So if you use white labs, subtract 4 months from the date on the vial and use that in the calculator

 

I just did YeastCalc as well.

2L starter @ 1080 OG @ 83% viability

Says you will end up with 364 billion with a stir plate.
Says you will end up with 235 billion by shaking it from time to time.

Are you using a stir plate? If I were you, I would go with the 2L on a stir plate if you have one, that should be fine.

 

And by viability, they mean the viability of the yeast you are putting in your starter, not the viability of the yeast after your starter grows

 

I have noticed yeastcalc drops it by ~10% / month of the manu date.

So 71% seems low to me and 96% way to high. I would go with YeastCalc around 83%.