Oftentimes, people put money into updating their kitchen and they want it to be "classic". Meaning, they want it to stand the test of time and be something that will transition well within the ever-changing design trends. I truly think it's impossible to design something that will ALWAYS be in style. However, I don't think it's impossible to design something that the homeowner will love for a long time. But that really depends on the home owner and what they like.
Right now, there are some key design trends that will most likely transition well as what's popular in kitchens evolves. So instead of telling you about a style that you'll never have to change again, we'll tell you about what's popular right now and you can decide if you like it or not and how it blends with your current (and/or future) furnishings.
Many people are getting more expressive and brave with their cabinet colors. Where white cabinets were the thing, blue or some version of it has become the new neutral in kitchens. It gives your cabinets a little color but this "color" is also pretty neutral and blends well with pretty much anything ---like jeans go with anything. You can mix blue cabinets with whites, greys, and wood tones. This gives your kitchen a lot of depth and makes it look way more custom.