Worth looking at this before posting https://www.newschoolers.com/forum/thread/543628/How-to-ask-for-ski-advice-
but preference for ski length varies greatly depending on a variety of factors including, but not limited to: height, weight, experience, skiing style, terrain choices, and then the many other variables of each and every ski like rocker profile, flex, sidecut, etc.
In a very
general statement, if you are an intermediate skier, you will probably decently happy with a ski that's about as long as you are tall. More experienced skiers, those that ski harder, and/or those that want more stability tend to use skis longer than they are tall (like in the case of the post above mine). If you are just getting into skiing maybe go with something a little shorter, that's what I did when I first started skiing. I skied 170cm skis, and I'm about 172cm tall. They were great for the first season, and some of the second, but they soon felt very short and left me wishing for more stability. Now, I'm happy skiing skis in the mid 180's, but am still happy skiing some in the high 170's or low 190's, depending on the characteristics of the skis.
If you give us some more info (height, weight, experience level, terrain you ski, and what skis you're looking at, etc...) we can offer some better advice.