Rhino Shield is your best value. It is independantly tested by BASF, carries a 25 year warranty based on that testing and only costs about 2X the cost of a professional paint job, when you compare apples to apples. Check out rhinoshield.net and you can email me at [email protected]
I'll be glad to give you any help I can. I've been painting houses for over 25 years and have been applying Rhino Shield since 2003. I am still impressed with every job I see even the ones done in '03,'04 and on.
If you want to go with traditional paint it will cost you more over about a 5 year period because of having to redo it. One thing is certain with all coatings is that preparation is critcal and there is no such thing as over doing it. We spend alot of time on that including wood repairs when needed.
If you want to use traditional paint, buy the best you can find. Ben. Moore and Sherwin Williams top line is what I used to use. Don't be fooled by "Lifetime Warranties" on paint labels. Read the details. They have all kinds of limitations and are usually not transferable warranties.