I would say both cars has its common problems, and would be largely be based on luck.
For practicality, go for Qashqai. It is higher, bigger boot space and more comfortable. Its presence would also be better. Considering that Qashqai is a very popular model, and it also shares a lot of parts with Renault, I would say spare parts (or even aftermarket upgrades) can be easily obtained.
For budget and better drive, go for the Mazda 3. SUVs/Crossovers cost of parts and its maintenance tend to be higher (i.e. bigger tyres, additional cost for car wash/paint protection, parts tend to be more expensive than their sedan/hatchback counterparts). Being smaller, they tend to be lighter and more fuel efficient.