Le Relais is a small resort that is located about 15 minutes from Québec city's downtown. It has a some nice parks (nice rails and boxes), but for jumps don't go there they have like nothing above 20 footers.
Stoneham is really the best park near Québec city, a little farther than Le Relais but it's worth it.
Sainte-Anne is like 40 minutes from québec city and has a decent park, but not better than Stoneham's.
You'll need a parkpass if you go to Stoneham and Sainte-Anne (it's 10$ for the season and is valid in Stoneham and in Saint-Anne.
Have fun in Québec!