I have been making miniatures for a living since 2003. Most of my time is spent working on contracts for clients- files that can take days and weeks to create because they are intended for commercial distribution.
The earlier files you will find here are some that I had created for my own uses at home that other people found useful- I call these 'fast sculpts' in that the printed miniature looks perfect but the 3d render isnt as nice or polished looking: Its a common issue in my business where the screen render has all sorts of details that are not visible when printed- just like your hamburger never looks like it does in the commercials when you get it in hand. The choice then becomes spend extra hours to make the picture look nice and charge you extra for that time- or just make minis that will print and paint just as well. I focus on making a printed figure that presents well instead of a flashy render.
Sizes: preference varies WILDLY and so my advise is to open the files and use a measuring device in the program to see if it is the exact size you wish- and then do a single test print. All files can usually be adjusted up or down within 10% (90-110%) without too many issues but if exact sizing matters be sure to test print first. In general the vast majority of stuff here will be very close to 1/48 scale in height. I have printed them all but your experience may vary with the printer you use and its settings.
I usually post a sample on Thingiverse. Those can be found here:
I also have a Shapeways store- most of the stuff here isnt on there as Shapeways is no longer my preferred print merchant (see list above) but I can put it there if you really want a figure and have no 3d printer of your own- just let me know :)