I'm going to continue this topic (knowing that it is old), because I've been looking everywhere for answers to almost your exact original question, and know that it will come up again in the future.
I too have to make an OJT selection for this year, and wanted to know which would be the 'best' choice for a 32U.
I found almost nothing I didn't already know, but a couple of personal experiences on this thread were useful. I basically searched for what kind of operations I would like to see myself participating in in the near-far future, and this as an opportunity to base my actual training/posting preference on firsthand experience.
I ended up searching for anything 'interesting' that the CF does with helicopters (I plan to ask for rotary wing as my first choice), and found as my choices:
442 sqn from comox (search, rescue, and transport?),
427 sqn from pet (SOAS),
CFS alert.
Please correct me if I am wrong on the transport side of 442.
I would like more information on Alert, if anyone has any... I know there's probably not much in the form of rotary wing up there, but it couldn't hurt to look at some fixed-wing aircraft as well. I chose Alert after talking to a couple of guys that spent awhile up there, but I'm not going to give off secondhand stories here. If anyone has spent time there, I would like to hear about it...