With my vision issues I find them all pretty hard to read, but mostly I don't want a lot of little tiny dots and ticks filling up my normal 1/4" cuts. For those that do minis or precision work, great, I don't really need anything smaller than 1/8 and that is rare as it is. For years I've been doing the cut large and trim down to exact, and I use templates mostly for the trimming.
Rulers are actually designed a little differently, some have the lines meant to be the cutting line, some are "next" to the cutting line, hardly makes a difference but I prefer to use the same brand of ruler throughout my cutting. Having said that, my main 6.5x24" ruler is a different brand, with a textured surface but I just love the way it grips for the long cuts.
To help me keep on track, I use tape a lot on my rulers to mark my cutting line, I have a roll of the 1/4" quilters masking tape in my sewing kit.
When I'm cutting "olfa green" colors or have troubles reading the ruler numbers like with black fabric, I slip a piece of paper or envelope along the measuring edge, that gives me better contrast and even if I can't read the ruler on the fabric, I can still read the ruler on the paper. The color of paper I use depends on the color I'm cutting, but white junk mail envelopes have a use!