The answer is: it depends...
Here is my opinion

1. Right now it looks like SPS is a better investment than cards. Chaos Legion set has some great card values, but it will be going out of modern in April or so.
2. You might be better off renting cards to play than to buy right now, that might change in the future. For example in the recent past I compared buying Chaos Legion Set and buying SPS vs Renting both and it was more profitable to rent everything. But only if you are paying 0.001 the lowest rental for SPS.
3. While renting SPS and Cards looks better now, if you want a lottery ticker in case we have a crypto bull run you would be better of buying SPS and possibly even cards...