I go with 20 post > 19 post mainly by the implications of 20 being able to beat the same Vegeta who ripped #19's hands and head off. Vegeta had to resort to bluff, otherwise he would lose. And the main cause of Vegeta's loss of energy was 19's absorptions, as implied by Piccolo:
Chapter: 345 (DBZ 151), P6.1-2
Context: after Vegeta scares No.20 away with a bluff
Piccolo: “He really had lost a lot of stamina…when he confirmed that the androids sucked out energy with the palms of their hands…He ought to have lost if he had fought that No.20 guy…But he talked as if he still had something up his sleeve…Vegeta really is a fighting genius…He might have sur-surpassed…Goku…”
There's also the fact that Vegeta dismissed the possibility of #19 being as fearsome as Trunks told them completely, while Piccolo had to think about two possibilities against Gero:
Vegeta at 19 post:
Chapter 343 (DBZ 149), P7.4
Vegeta: “I’ve realized by watching your faint movements up to now…That you guys don’t seem as terrible as the rumors made out.”
Piccolo at 20 post:
Chapter: 347 (DBZ 153), P3.2-3
Piccolo: “It seems that in the original history, we were supposed to be wiped out by you two androids…But it looks like the future has changed somehow…Was it that you weren’t as strong as we thought?...Or have we grown too strong?...
Not to mention hints like 20's speed being higher than what Vegeta thought, or 20 not being still too concerned with 19's new powers aftet Goku's fight, all which imply a good difference between 20 and 19.
If Piccolo could defeat 20 post without problems, then he could do the same to 19 as well.
Piccolo opting to "play dead" was more because his aim was to save Goku. He still wasn't too sure about 20's capabilities, so it just shows he didn't want to possible engage into a troublesome match against him and risk getting Goku killed. It was a smart move to save Goku. He still stood tall when Kuririn purposed retreat, even when he didn't know Vegeta had SSJ, which shows he would still be able to handle both androids imo.