When I used to detail the car myself (now I leave it to a friend who is a professional detailer) I found that the best products in terms of protection, shine and value for money are the ones from ZAINO (
www.zainoeurope.com/). I also used for a year or so Swisswax products, which are excellent as well but quite expensive.
If you apply the Zaino products properly, then they can last for as long as 6 months under harsh conditions (i.e. rain, mud and sun). A recommended process is the folowing:
1. Wash the car (2 bucket technique)
2. Clay
3. Wash again
4. Apply ZAIO (all in one)
5. Apply Zaino Z3 or Z5 (with ZFX even better) and do 2 or 3 coats with Z6 between coats.
6. Finish with Z-CS
Maintain with Z6 or Z8 (even better!) and wash with Z7.
Of course all of the above give an excellent result but take ALOT of time!! You can break the steps and do 1-4 in one day and then another day, wash again the car and do steps 5 and 6.