With how low the market is right now, I'd be purchasing stocks through TFSAs instead of RRSPs because...
1) In either investment vehicle, the sales would be exempt from capital gains taxes provided you buy/sell from within the plan.
2) As economic times are uncertain - by purchasing through a TFSA instead of an RRSP, the funds are still accessible without adverse tax consequences. That is, if I needed the money later in 2020, I could withdraw it from my TFSA without increasing my taxable income (not the case for RRSPs)... there are some more intricate rules for TFSAs here if you're close to your TFSA limit, but if you're well below it, you should be fine (talk to your financial advisor if you're unsure).
3) As most of us are, to some degree, working less, we'll likely be earning less income for 2020, meaning the main pro RRSPs have over TFSAs (an upfront tax deduction), is much less advantageous - as most of us will be in a lower earning bracket (thus saving less marginal tax) for 2020 at least. Of course, if you really like contributing to RRSPs, you could choose to carry forward the RRSP deductions to a future taxation year.