I use the Zaino line of products. Amazing stuff! I also only use a cotton mit-egyptian cotton preferably.
With the Zaino products, you wash your car with Dawn first to strip the old wax. I find that once I apply all of the steps required with their products that I only have to re-apply the 'wax' portion once every six months or so. Water beads up until that point and beyond.

__________________
1982 Silver 300DT

I've been using Eagle One for a few years now and really like the stuff. It does a good job of not stripping the wax off. I'm currently using it with that Eagle One spray wax. I'm happy with the results. If I use my buffer, I put on Meguiar's Gold wax.

__________________
ARVY

1999 E430
1999 C230 Kompressor
1992 300E (write-off)
1984 190D 2.2 (sold)