I picked it.
The surprise for me tonight was Aisha having such a high vote. She hasn't featured much in the edits.
Lisa, while she brought drama, didn't have enough redeemable qualities to appeal to voters, hence was discarded. A similar thing happened with Katie.
David benefitted largely from that confrontation; there was a lot of sympathy voting being thrown his way in the last few days. Lisa staying would have perpetuated that, so now if he's to keep his popularity, he'll have to confront the likes of Sam, Ryan and Lawson for their behaviours toward him (i.e. challenge the status quo).
As someone mentioned earlier, if Cat's incident with Lawson in the sanctuary had happened, and was shown earlier in the week, she would've left tonight. If she's nominated again, I think it's almost guaranteed that she'll go.