Having now flown on the new configuration on the 757 I can confirm that row 1 does indeed have a larger cutout (since it doesn't have to be squeezed between the seats of the next row forward) and I agree that it is the one to choose.

In addition I would point out that the window seats in the other rows have a somewhat wider cutout than (extremely narrow) footwell of the aisle seats. So if you get the window seat there is some compensation for having to clamber over your seat mate.

All in all a very good seat IMO. (BTW I noticed that very few people lowered the arm rest - the control is not very noticeable - thereby denying themselves the extra width.)