Hi.
There are many factors and situation involved in deciding which immigration stream would work best for you like how long is your work permit valid, would you require a BOWP in next 6 months because PGWP is one time open work permit given to students post completion of studies in Canada. Unlike AIPP and other provincial programs, in express entry IRCC goes by Comprehensive Ranking System score(Age, Education, Work Experience (In Canada+Foreign Work Experience, English language proficiency(IELTS), similar factors for Spousal score. First and foremost, you will have to check the last cut-off score for CEC (I am not sure what's the current frequency of draw for this stream at the moment) and then compare your score, if you meet the minimum entry criteria for express entry and have a score well above the last cut-off then you can create your express entry profile and get in the pool. In the next draw you will receive an invitation to apply (ITA).
After you accept ITA, you will see a list of document checklist to be uploaded and after you upload all the documents and submit you application, you will automatically receive AOR in your mycic account, its completely online. The AOR can be used to apply for Bridging Open Work Permit(BOWP) in case a person is nearing to the expiry of the existing work permit in Canada. This is the main difference and issue with AIPP, it is a paper based application which requires someone to manually check your paper application and then log it into the system for completeness check after which you will receive the AOR.
My experience with AIPP:
I submitted my paper application in the first week of Feb 2020 and followed up after a month with IRCC, I did get a temporary file no. and was told to wait until end of Mar 2020 for the AOR and that in standard times it takes 90 days to receive an AOR for paper application but after COVID-19 everything changed, I still followed up but there was no progress made until end of May 2020 on my file (where I was thinking that it will get approved by then based on previous application processing times). The other fact I discovered is post-covid, processing times in general for any program indicated on IRCC website are not guaranteed unlike before express entry applications were required to be processed within 6 months but still there was no guarantee for AIPP even if it says 6 months.
My experience with CEC:
In June 2020, I was well above my 1 year experience in Canada and my CRS score was above 500. so I decided to apply under CEC stream of express entry. I got the ITA in June and submitted my application in Jul. I waited for almost a month for my police certificate from my home country because it expired. I received the AOR immediately upon submission of my application. My medicals and biometrics took 2 months to pass and completed. For biometrics, I would say it was just the timing that worked for me because, it stalled express entry application from Mar 2020 because Service Canada offices were closed for finger print collection and those services resumed just around same time when my medicals passed and I received the biometrics letter). So far, I am well within the processing timeframe of 6 months for express entry and have passed critical stages of application like eligibility, medicals, criminality), now waiting for security and final review by the officer for COPR. I haven't heard anything since a month and a half from IRCC. No additional docs. I hope that happens soon.
Now, the usual processing times are definitely impacted even for express entry but at least people are still able to track their applications and there is a progress made.
Post COVID, applicants (including me) were sceptical and develop many theories but the fact is IRCC is working under reduced capacity, certain NOCs are prioritized based on labour market demands and delayed responses from partner organizations like CSIS, CBSA are still causing processing delays.
I hope this will help you in making a decision. Let me know if you have any further questions.