Selfish part of me says pick Ottawa so my chances increase of getting into Queens!
I met some Queens MPA kids in the program currently, vaguely remember them telling me they got something like 3k in grants, and there's some opportunities to RA but no TAships available. If you qualify for OSAP and get grant money from that, tuition is pretty low. Depends on your lifestyle but living in a town like Kingston where there's nothing to do is cheaper than living in a city too.
Take what I say with a grain of salt, I haven't researched much about MPA programs so I can't really compare but Queen's MPA is a great program IMO. Its rigorous since it's condensed into one year, but the students are very very tight knit and "team oriented." The program is also pretty centered on students needs, and there's a lot of flexibility in courses and additional services. From what I gathered there's a really strong connection with the OPS, although Ottawa probably wins with the federal connections. The Queen's program pretty established and is really well respected within the gov't though, I worked at the OPS this summer and there was a lot of MPA alumni, and the program was recommended to me a lot (that being said I'm in my undergrad at Queen's right now, so I don't know if I just happened to have selective memory with running into Queen's alumni). Queen's also has a cult-like feel so there's a strong networking opportunity, and alumni love each other.
For cons though, Kingston is awful although it's pretty fun if you're here for just one year (literally my only hesitation with accepting Queen's MPA if I get in is I don't know if I can do another year of this place)