Blade and stroke speed are as important as the saw. Someone at Home Depot or your hardware store should aim you to the correct product. Things like the length, teeth per inch and type of material you're cutting. Also, if you cut tight curves you might want a blade that's not too wide. Wider blades are good for straight and wider radius cuts.
Last winter I cut up an old oil tank in my basement with reciprocating saw. I searched the internet and found a guy on youtube who cut up a tank with one blade. I thought it was proof enough so I found a pack of said blades on eBay and they didn't disappoint.
Buy the best blade for your specific job, you won't regret it.
