A good place to look are the High School Rankings for Ontario and see how Ottawa schools do. In terms of what is offered, Ashbury College (private) and Lisgar (public) offer International Baccalaureate programs (IB) that can often skip students ahead a year at university and offer very good advanced placement. Lisgar is a difficult school to get into if you do not live in the Lowertown/Downtown region, however.
Canterbury HS is an arts school that, while does have good networks and excellent teaching, is a waste of commuting time and a bit overrated if you are not passionate about the arts (drama/music/writing/etc).
John McCrae HS in Barrhaven has a good name as far as public schools go, as does Earl of March in Kanata and even West Carleton, in the far west end towards Carp and Dunrobin.
In terms of Catholic schools, Immaculata is a good school and has a more conservative tone, but due to its urban setting, it can have a good vibe. Some of the Catholic schools in the west end are also good: All Saints and Sacred Heart to name two.
Finally, the French schools in Ottawa are good if you want to pick up a second language quickly, however can be a bit of a challenge if you're not familiar with French. De La Salle has a great sports program. Ecole secondaire catholique Garneau (Catholic school) in Orleans also has a great name amongst the French-language schools.
Hopefully that gives you a good idea of the schools in Ottawa. Most are fairly decent, however there are a few you should stay away from (Ridgemont, Brookfield, St. Patrick), but to be honest, there aren't many schools that I would say are worth commuting halfway across the city for during rush hour anyway.
Good luck!