And I also realise the physical pitch itself has also been re-laid multiple times, but afaik the location/position of the pitch has been the same since the beginning? So for me keeping the pitch where it is the most important.
If we can't do a stand by stand rebuild, (due to time and costs/disruptions) then my 2nd choice would be to keep the OT pitch, then reduce the size of the stands (keeping the most historic South Stand largely as it is with the Munich tunnel etc, the most historic part is the old players entrance tunnel I think), and downsize OT to maybe a 25000 seater stadium, to be used by the United Woman's and Youth teams. I think that would be great for promoting Women and Youth football.
Then after reducing the footprint of OT, hopefully there is enough space to build a "state of the art" 100,000 stadium. Why 100k? well for me it's "go big or go home", if we're going all the trouble of building a new stadium, might as well go big and have a stadium that's going to last us 50+ years before any major works needs to done again, also having the bragging rights as the largest stadium in the UK. Also the seats that's right at the top might not have the best views, so those can be made significantly cheaper for younger fans or general admission, in order to attract the next generation of fans.
But looking at all the pics/maps used in various reports on news websites, even with a reduced size OT, they all overlay the new stadium onto the Freight Terminal, that might be a problem, as I don't think the club owns it, and extra costs and disruptions having to purchase it.