I am new here but had the same dilemma! I chose a gray liner ultimately (this is the liner i chose -
Island Granite
) because I felt it was more modern and went with my decor better.. I felt the very blue ones, and especially with the borders, looked kinda 80's.. I based my decision off of googling images and also googling videos of actual people who used the specific liners so I could see some real life applications.. I also looked at what was shown in the books from the patio paver companies as to what looked nice with the stone we selected, then sought out those colors.. Another option is to ask the installer if any of the customers used those liners, then check them out in person! Anyway, hope it was somewhat helpful - Oh, and check the liner company's facebook, or search those liner names on facebook to find videos as well! Good luck!