I find sleeping in WT impossible, WT+ slightly easier and the overall space is much better.

leg room is significant in WT+ and you re able to stretch out a fair bit and width is slightly better. That said, until you get to Club World, the space is only incremental.

I personally really like WT+ as it's quieter, the space is humane, food a bit better and service a little quicker. The smaller cabin makes a decent difference and like I said, you are able to get a few naps in (although I only really sleep well on a flight in club or first).

I don't think being pregnant will make much difference to the decision except maybe having a foot rest in WT+ ?? Also row 51 in economy can get slightly bumpy being at the back of the plane, so sickness might be an issue?