As previously posted, the longest lasting protection for paint is a coating, but the cost is high and the coating will not provide the same level of gloss or depth as a sealant or wax.
If the cost of the coating is too high, and you don't mind doing some work and learning a few techniques, then the best option is a paint sealant. A synthetic sealant will last longer that a traditional carnauba wax, but again the trade-off is that a wax will typically have more gloss and depth. Most people choose a sealant for the longer life on a daily driver or a vehicle that lives outside 24/7/365.
In response to other posts, I will assert that even "modern" paint needs protection from the elements to remain looking good. Acid rain, bird-droppings, tree sap, brake dust, road tar, and other junk has the very real potential to cause etching or other damage to the clear coat. In addition, rain and UV exposure absolutely will cause fading and drying out of the plastic and rubber trim, if left protected.
Note that neither a coating, paint sealant, or wax is applied to plastic or rubber trim, so these finishes need other protection. There are some sealants that can be applied to this trim to provide UV protection, or a more traditional trim dressing can be used, if it specifically lists UV protection. It is not hard to find a multitude of vehicle that are only a few years old that have black trim faded out to gray.
Further, having protection on the paint and trim also makes washing easier, as the junk that ends up on the vehicle is much, much easier to clean off, without having to scrub hard or use harsh cleaners.
The argument that "it is just a car" does not make any sense. These vehicles are expensive, and some preventative maintenance can keep them looking good. If you don't have any desire to spend time and money keeping your vehicle looking nice, and your only goal is for it to be "not dirty", then that is your choice, but it certainly does not warrant ridicule for those who choose to do so.
In addition, detailing is a hobby that many, including myself, enjoy doing and get satisfaction from having a vehicle that looks new, or even better than new, years and years later. Granted, this is not the case with the vast majority of the vehicles on the road.
The statement that these people need to "get a life" makes no sense, as the same statement could be made in response to any activity or hobby that does not interest you. For example, anyone that spends four hours each Saturday trying to hit a little white ball into a hole needs to "get a life". Anyone who spends most of a Sunday watching sports on TV needs to "get a life". Anyone who stays up late playing video games needs to "get a life". Anyone who gardens and grows their own food...you get the point. These are all activities that may interest some people, but not others.
To share a few addition tips to those interested, do not use dish soap on your vehicle, if used regularly it will dry out a cause fading to plastic and rubber trim. There are specific products that can be used to strip sealants and waxes, but for routine washing a pH balance car wash shampoo should be used. Also note that cheap shampoos do not provide the same performance as higher quality products do. When washing, the key to not introducing swirls and scratches is to have a shampoo that provides lots of lubrication to safely remove the dirt and crud from the vehicle.
Also, automatic car washes cause swirls and scratches with the dirty brushes, and touchless car washes use harsh chemicals that dry out and fade the trim. I have seen cars only a few years old that make weekly trips trough the tunnel-wash, and look 20 years old. Also, the harsh chemicals used will strip off any wax or sealant that you have applied.
I know, too long, didn't read. But if you read this far, and are interested in learning additional information, here is a detailing thread that I created for my Ford Raptor:
http://www.fordraptorforum.com/f36/first-detail-adamized-raptor-33281/#post664813
My apologies for the re-direction to another forum, but my new 2016 Sport is still a few weeks from delivery. Once it arrives, it will be machine polished, with sealant applied to the paint, trim and wheels.
And a photo showing what a machine polished, fully detailed, properly protected vehicle can look like. This was photo taken at 14 months old, right after being polished for the first time.
The truck is a daily driver, sleeps in the garage, and enjoys some off-roading fun in the sand dunes a couple times each year!
Most of my driving is in the Winter months.
