I can't recommend taxtips.ca or the Canadian Financial Wisdom Forum enough, (FWF has a wiki and a discussion page). Both sites give great in depth explanation all about RRSP, tax rates, whatnot. Taxtips is great for their calculators as well, to see what and how you can move your tax planning around as well, especially for your future.
If I were making 45k again, I would certainly have a maxed TFSA (for the access, because tax free,) then the employer RSP, personal RSP and always last a taxable account. Deferred taxes are always better than current taxes (as mentioned above, RSPs give you tax free growth that can't be understated.
Also, I don't have a reference, but there's good consideration to the higher taxes paid at different rates. I typically look at the 45k point as possibly being close to the tipping point. Above that, the higher current tax rate is much steeper, the lower the wage however means you may not get the return you were hoping.
Taxables in some provinces are negative tax, OP is in one of those provinces. Only a TFSA has tax free growth, the RRSP has tax deferred growth. We should never say RRSP is tax free, its very misleading and is a fundamental flaw when comparing RRSP vs. taxable accounts.
My wife, who is 38, just sold from from her taxable account this year, gains of $10000. Expected taxes are zero, she's in retirement already. Dividends have long been tax free, as long as they're eligible (of course they are). Taxable accounts were the preferred option over RRSP for many low income people before the introduction of TFSA, what's changed? If the same amount was withdrawn from an RRSP it would boost our household income, lessening CCB currently (5.7% secret tax). Because its gains she has a further $7000 of room for more gains, or we can pull $7000 from the RRSP tax free. On that investment, we've never paid taxes and now we never will.
A taxable account is your best friend if you take off a few years for children, early retire, take a sabbatical or gap year. Its also the perfect hedge against too much in a RRSP too early. Although I call it a taxable account, we don't pay taxes on it. She started the acccount while earning $30-40k/year. In my taxable account I hold Horizons products (thanks to a forum recommendation), I don't pay tax on it. I never will, just like my TFSA.
Don't overlook taxable accounts, they're awesome. Although I also have maxed RRSP and TFSA, I'm still a fan of my taxable account, its pretty much another TFSA for me. Everyone has a different situation, everyone has nuances, loads of low income people do better by contributing to all three accounts simultaneously.
If I was following a couch potato strategy for a low income (under $45k in BC):
TFSA - US ETF and rest of world (high growth stuff)
Taxable - CDN ETF (eligible dividends negative tax in BC, reduces taxes owed each year)
RRSP - bonds and whatever is needed to achieve balance (more US/world), balance is better than tax status.
I welcome thoughts and critiques. Since I'm following this strategy myself, feel free to point out mistakes. I also do buy/hold, thats a key assumption.