The comment of the OP's regarding the layout vs size is a very valid one, as being here since the start of both being put into production, I have witnessed many folks who thought the 19 was the one for them based on layout, and some of these folks were swayed to the added space of the 21 only after seeing it.
We too did were not bothered by the climb over, which could be nice. But too be honest, we often did the step over, and started to actually both deal with the middle of the night bathroom trip at the same time. While not these best possible scenario, it was one that we gladly put up with for the bed location.
The mattress in the 19 is not a queen wedged into a double bed space, as other than the curved corners it was a full 60"x90" queen. We never had issue with moisture, likely due to our climate. Making of the bed was only an issue with the fitted sheet, but that only got replaced once a trip most times. When we got the replacement mattress, we did get it 2 " smaller each way, something anyone could do.
That term "personal preference" gets used a lot, but it is so true. Cathy commented that she likes that the curtain keeps the sun out in the morning, while I really like waking up to the sun. For me, those three windows around the bed are great! I love having the view in the morning and when we are in the trailer during the day I'll often read or use my computer on the bed. We eat most meals outside so the view out the front has never been an issue. The storage and the counter space is appealing -- very appealing -- in the 21, but our particular goal was to find the smallest trailer we could get that had a queen size bed. There are times when I wish I didn't need to climb over Terry to get out but for us that is offset by the size.
Other than never hanging out on the bed, or at the dinette either, this take pretty much parallels mine. I did read in bed just before falling asleep though.
I know it is not for everyone, but for us the best view is not at the rear of the trailer, but is actually in the "living room", thus the reason we prefer to spend our time out there.
My brother just went through the 19 vs 21 thing last year, and it was not just the layout of the 19 that they preferred, they actually ordered it because of the slightly smaller size and weight, and knew from us using it that there was more than enough storage space. They wanted to use their Honda Pilot to tow, or when it needs replacing buy a vehicle of similar sizes, and the 21 was pushing the limits for doing this. They are coming from owning the same tent trailer and three kids for 20 years, and are really looking forward to the convenience and warmth the 19 will afford them.
There is no wrong choice in deciding which model to choose, only ones individual choice that really matters.