There's also a guide for the best sites to buy bitcoin:
https://www.bestbitcoinexchange.io/ which can be good to reference whenever a new bitcoiner asks this question.
As other users have stated here, Kraken or Bitstamp are currently the most popular bitcoin exchanges. The former has plenty of Canadian users too but only accepts wire / SEPA deposits, while the latter is currently the best bitcoin exchange in the UK and Europe - and accepts credit cards.
Alternatively Coinbase would be the easiest exchange to use, in terms of the UI, buying, and withdrawing. Though some users report long customer service reply times, and temporary account freezes. I would still recommend this service to any new users in the US, Canada, UK, or Europe. They accept bank transfers, visa, mastercard, and users in the USA can withdraw small amounts through PayPal.
Should you like to get technical, I would recommend trying Bitsquare. It's a new decentralized p2p exchange which is becoming quite successful. To use it you'll have to download the client software and watch a few youtube tutorials, but once you're comfortable with using it you'll be considered an expert!
If you want to buy directly of people in your area (Cananda, or anywhere in the world), then Localbitcoins would be a great bitcoin exchange to use (it's like a centralized website version of Bitsquare). You can buy btc with cash, SEPA transfer, and even PayPal.