I like Oysteilo’s choices except I would hesitate on the sub in 110, the inf in Yunnan, and the transport in 71.
Yunnan increases the chances for a Yunnan disaster for Japan, but Japan is almost always going to go for it and the most likely outcome is just China losing one more inf.
The transport is probably only useful if you are fairly sure you are going to hit the Italians first in Ethiopia. But I think they often have other priorities that would demand the other units needed.I suppose it can go to Persia to allow the India transport to go to the islands, but I think the islands are often a mistake on UK1.
The sub in 110 is useful because the naval base gives it range but it doesn’t add much to the defense since the German attack there is mostly air and because that is the one spot the Germans are definitely going to hit. 106 may be more useful for defense since it likely blocks that attack or forces the Germans to send 3 subs (in which case the sub can submerge and join the counter)
UK Europe is almost always the best bet for the bulk of the bid since that is the one ally that is certain to be at war in round 1, (so I agree with Oysteilo’s emphasis on that) but I might still consider adding to the pacific. More UK inf in the pacific, or a second ANZAC sub, or Art for China.
Also, the sub in 91 is for me a must, as it discourages an attack on that cruiser (which is an option for Germany if they ignore 111 or 106) and it threatens everywhere the German navy ends up plus the Italian destroyer in 96.
But I haven’t really played much OOB for a while (and never had a chance to play with a 50 bid) so I might be misjudging and identifying things that are more appropriate for BM.