There are pros and cons with inland vs. outland.
Inland is based on you staying in Canada throughout the processing. If you end up leaving Canada during this time and for any reason are denied entry to get back in, your inland is gone. If you do an inland application, you can expect your first stage approval in about 6 months if all goes well. At that point, you can get health care and an open work permit. You can expect your PR in 12-18 months, if all goes well. The drawback with inland is when it doesn't go well. If Vegreville is not convinced of your relationship or they have any questions causing them to want an interview, they will forward your file to your local CIC office in Ontario and you will have to wait for them to have time for your interview. Depending on the caseload of your local office, your application could be sitting on the shelf for 1-3 years and in the meantime, you are stuck in Canada with no health care and no work permit. The pros with inland are that they will not kick you out while you are waiting.
Outland is basically asking for your application to be processed in your country of nationality but that doesn't mean you have to be there. Mississauga takes 36 days to approve your spouse as your sponsor but after that, your application is sent to your country of nationality and takes another few months there, see http://www.cic.gc.ca/english/information/times/international/05-fc-spouses.asp There is no work permit with outland but the processing time is usually shorter. The drawback with outland is that if there's an interview required, you will have to go to the country where your application is being processed and you don't really have a claim to stay in Canada so if you end up out of status and apply to change your status to visitor while you are waiting, they don't really have to let you stay although I imagine they would in most cases. Since you are legally residing in Canada, you could also ask to have your application processed in the US if it's better for you but make sure you can get a visa to travel to the US if you have to have an interview.