I was told by someone that rice vinegar was not suitable to be used in a salad dressing.
Can only certain types of vinegars be used for salads?
Rice vinegar is less acidic than other vinegars; as such, you need to adjust your oil-to-vinegar ratio or it'll might seem overly oily.
Rather than the 3:1 oil-to-vinegar ratio, or rice wine vinegar I'll go with a 1:1 mix. If it's a seasoned rice wine, I'll sometimes leave the oil out entirely, but I seem to like sour flavors more than other people.
You can use most any vinegar or even acid from citrus fruits for salad dressings, although I don't know that I'd use white vinegar.
One of my favorite dressings is made with a base of rice vinegar, sesame oil, and ginger. There is nothing besides your personal taste to rule out what vinegar should be used for salads.
That said, I'd personally avoid malt vinegar.
For me, nothing beats balsamic vinegar. The 12 years aged one is still affordable enough to be put on the salad, but I don't recommend it unless you don't like acidity. If you are an sour lover like me, the normal non-aged balsamic vinegar is a good choice.
As a very rare alternative for salad dressing, I recommend honey from the Strawberry tree. It is very rare to find, because it blooms in December and it's too cold for bees, but the taste is very bitter and it goes perfectly on salad.
Yeah, that's nonsensical advice from your friend. Match the vinegar to the ingredients, season, and other components of your meal. E.g. rice vinegar can be lovely in an Asian context, and it is also prety neutrally flavored so it can have more general use. I generally avoid flavored vinegars (I can add my own flavors), but there are some great varietal wine vinegars out there - search "Katz" vinegars for one example. Or try lemon or lime juice for an altogether different alternative.