I really don't think there is a definitive "correct size" or scale for our figures. I have made comparisons of all the different figures that I have and there is a very noticeable difference in proportions not so much in height but in body build.
Here is a quote from a discussion on Miniature scale that is very interesting:
Two Measures of Scale
The size of a miniature, relative to what it is a replica of, is known as the scale of the figure. For no particularly good reason, two different systems are used to rate scale.
• Some scales are given as a ratio, variously written as either a ratio (i.e., 1:300 or 1.300) or a fraction (i.e., 1/300). The number on the right of the pair indicates how many units (inches or centimeters) on the original are equivalent to one unit on the replica. For example, with a 1:300 scale miniature, if the miniature is 1" long, then the original was 300" in length. In spoken English, you would say 1/300 as "one [pause] three hundred scale."
• Other scales are simply listed as a certain height, such as 15mm or 54mm. Most people usually think of this as being the height of an average man (i.e., in 15mm scale, men are 15mm high), but there is a lot of confusion on this issue. According to some experts (but not all), "traditional" figure heights are measured to eye level, since measuring to the top of the head is impractical for figures wearing headgear (as many military figures do). Therefore, when a manufacturer says his figures are (for instance) 25mm scale, he might mean "25mm to top of the head" or "25mm to eye level."
Just to confuse things further, manufacturers have been slowly making their figures a bit larger in recent years. The extra size gives more room for details, so that a "large 15mm" figure often looks sharper than a "classic 15mm" figure - and that's because it's not actually a 15mm figure, but (often) an 18mm figure! The same is true with 25mm figures, as represented by the miniatures put out by Games Workshop as well as by Reaper's "heroic" 25mm figures (both of which measure closer to 28mm in scale).
As a final note, even figures which ostensibly are in the same scale may differ considerably in body build, head size, and general sculpting style - even when made by the same manufacturer! (For instance, older figures vs. newer figures from the same company.) Styles may differ considerably, as some manufacturers see their goal as to make scale replicas, while others concentrate on making "gaming pieces" which are inexpensive, durable, or easy to paint. Plastic figures may be sculpted in a thinner style than metal figures. Therefore, if you are concerned whether you can mix figures from different product lines or companies and have them look appropriate, you may first want to order samples from the manufacturer. (
http://theminiaturespage.com/ref/scales.html)
IS OUR GOAL TO MAKE SCALE REPLICAS OR GAMING PIECES???