There are 3 very nice Monofiliments on the market. Superior's Monopoly (a polyester), Filtec Essence (a nylon) and YLI Wonder Invisible also a nylon. Nylon monofiliment did have a reputation of turning brittle over time and was also notorious for not being able to handle heat, be it iron (which would commonly melt it), dryer heat (which would turn it brittle) or even heat from direct sunlight or being stored in a vehicle for extended periods of time in hot climates. I honestly don't know if the manufacturers have changed this in some way. I can say it is no longer the stiff "fishing line" we remember from 20 years ago. Today's monos are very fine and flexible and not pokey at all. Some can be picky as far as tensions are concerned but I have had extremely good experiences with monofiliment. I use monofiliment for ditch work and I have also used it to machine blanket stitch fused applique with no issues. But for background quilting and all over designs I prefer a fine thread that "plays" nicely with the colors in the quilt. Invisifil thread by Wonderfil is a lovely 100 wt polyester (fine as silk) that sinks right down in doesn't show much. I have found that grays and golds seem to compliment just about any color as well as a sage green shade.
If you are truly concerned about the longevity of the quilting, you may want to consider going with a light weight thread as opposed to monofiliment.