He specified safe so "bank stock" is out because it's still stock, and even bank stocks can crash in value by 20-25% on a downturn. Yeah, we haven't had one of those for 20 years or so, but we could.
If you insist on safe you are insisting on fixed income. No SINGLE bond is really the "best and safe" you want a combination of bonds. That way if one tanks, you're ok, because it's just a tiny little piece of yoru pie. This is called "diversification" and it is a Good Thing.
Now if you are absolutely loaded with millions you just go down the list of all the major A+ rated corporate bonds in Canada and buy them all. You've got the money to do it, why not. If you have something under a million you are going to have to make due with a bond fund.
In evaluating bond funds you have three basic questions: what's the yield? how diversified is it? and what's it going to cost me? In short you want the highest yield with the broadest diversification for the lowest cost. When we talk about cost we are talking about the MER, the management expense ratio, which is the percentage of your invested money they put into their pocket every year.
Note that this approach assumes you are going to invest your money for well over a year, and that you have several thousand dollars to invest. If it's less than a year or less than a couple of thousand you're better off with an ING Direct account or some such, since there are fees you will pay to get into and out of this investment. After a year or so it's a wash, but for a shorter time period, avoid the fees entirely, and take the lower no-fee interest rate from ING Direct or some similar bank.
All that said, if you are investing +20-100k or so look at some of the really low MER mutual funds from companies like Phillip, Hagar, and North (PH&N), they have some bond index funds for pretty cheap with good diversity. Go for a broad corporate fund or some such. Another alternative is to buy a bond ETF on the stock market like Barclay's ishares XBB, which holds a broad array of Canadian bonds including govt. and corporate. Use a discount brokerage for that, you'll pay $20-25 to buy into your position and $20-25 to get out of it depending on your broker.
Note that bond income generates taxes each and every year. If you are planning to hold for a long time and you can suffer a little more risk (like 20% in a downturn) you might really be better off holding an array of blue chip corporate stocks. Dividends are preferentially taxed, and you might be able to avoid the capital gains tax until the year you sell--if that's many years off, that's a lot of tax-free compounding. Again you are seeking broad diversification and low cost. There are a variety of index funds that cover the TSX/S&P 60, like the ishares XIC that trades on the TSX. You want to pick the one that has the lowest MER. All the TSX indexes are selling the same thing, so buying a higher MER one is dumb.
Note that if you go the index fund route, while it's reasonably safe, you are definately still exposed to market risk. You'll get the average return for the whole TSX, and it's heavily weighted by big banks and large Canadian firms, but absolutely in a recession or severe downturn it'll lose some value. This is something you'll have to decide for yourself--just remember that ANY stock you buy, no matter how blue chip, can lose value. If that worries you, go for the diversified bond fund.