Hey there.
Ultimately, this is a really hard question for us to answer. For one, we have no clue what is inside of your TFSA or RRSP. For example, if those accounts contained all Canadian equities, you may want to branch out of Canada. If it contains all international, I'd suggest maybe you'd want to look here at home.
Then it boils down to risk tolerance. If your other accounts are all stocks, you'd have to understand if you're comfortable with an all equity allocation, or if you should be sprinkling some fixed income in there.
All these variables are why it makes it literally impossible for us to answer any specific question like this, primarily because we have no idea on a specific members financial situation.
However, eliminating ALL outside variables like this, here is my thought process.
If you're comfortable with handling more stocks, and you like the idea of individual stock ownership, by all means add more. Everyone should essentially have a threshold they're comfortable with. For me, I'm involved in the markets 8 hours a day here at Stocktrades, and have a lot of experience. So holding 20+ stocks for me isn't an issue. For someone who doesn't have as much time or knowledge, it may be too cumbersome.
In terms of ETFs, I hold them myself for investments outside of Canada. I am laser focused on the Canadian markets, and instead use index funds to give me US and International exposure. This allows me to not only deliver better quality research for Stocktrades Premium, but allows me to stick to what I'm good at.
Keep in mind, now that you're dealing with a taxable account, a lot of different tax implications come into play as well. For example, fixed income interest is taxed like normal income, whereas capital gains are taxed the most favorably, and dividends from Canadian companies have significant tax advantages as well with the dividend tax credit.
I'd LOVE to give you a concrete answer, but as I mentioned it's just near impsosible!