Low iron definitely looks better, but I would strongly suggest never using a magnet scraper if you want to stay scratch-free. If you scrape by hand, you will have scratch-free glass for years.
I started using a magnet scraper with a blade that I do not leave in in tank. I did this because I was snapping off acros every time I cleaned the glass because when you scrape by hand, the angle you need requires your hand/wrist/arm to be several inches away from the glass and the acros had grown to a point where this was happening.
I clean the glass by hand in a small area before I put the magnet scraper in the tank, so as to avoid putting it on top of any small debris that could scratch the glass. It doesn't matter, because within a couple months, I had tons of scratches. And there were no anomalies on the blade. Scratches with magnet scrapers are unavoidable.
So there are a few solutions:
1) If your tank is large enough, keep corals far enough from the glass so that you can clean by hand without breaking them.
2) Don't get low iron glass - but regular glass is probably going to scratch eventually too with a magnet scraper
3) Use a magnet scraper, but know that you will inevitably end up with scratches.
Here's a final piece of advice...even though I have some scratches, my tank looks good, so you don't even notice them during casual viewing, and I am the most detail aware person on the planet. And I have seen much better looking tanks than mine that had horrible craftsmanship, and you only notice because you intentionally looked for it. The corals and fish looked incredible and that is what you see.
In other words, if your corals and fish are beautiful, you are not going to care about a random scratch or ugly silicone. Most hobbyists would be better served by studying art principles like negative space, color theory, etc. than they are by spending $10k on a tank when they could get a slightly lower quality one for $2k. I've seen plenty of people with Reef Savvy tanks that are of the highest quality, but the tank looked awful.