Surforms are not quite rasps. Stanley started making them after the success of the Microplane company. I've only used a surform a few times, wasn't very impressed. I have 2 Microplanes, which seem to be made of harder metal, and the teeth start out very sharp. One is almost worn out. Unfortunately, that one was not made to have a replacement blade. So expect to buy replacement parts if you go w. that type of tool.
True rasps are more like files, but generally have coarser ridges and teeth, being used on wood, not metal. They last for a very long time. I still have a Nicholson 4-in-hand that I bought 40 years ago. It has finally dulled enough that its not very useful. They still sell for less than $10, so are a very good buy as a base level tool. I see Stanley also makes a similar rasp.
Auriou rasps are exceptional, but also very expensive, being all hand made. I have a few that were Christmas and birthday gifts to myself. Wonderful tools. Because they are handmade, they do not produce regular ridges in the wood, as machine formed rasps do. They are getting lots of use, and I hope they last. I believe Gramercy tools also has hand made rasps that are somewhat less expensive.
I also have a few Iwasaki carving rasps. Quite sharp and aggressive. Cost a fraction of what the Auriou do, but they don't have any as large as what Auriou makes. Do leave regular tool marks, which must then be sanded or scraped away.