I'm ok with banning martial adepts.
If and only if you also ban everything in Tiers 1-3.
Show your DM Fochlucan Lyrist from complete adventurer, and ask him how someone would get through all 10 levels of that class in 20 levels without xp penalties. When he can't answer, ask him how one would even get into the class without xp penalties. This should be proof that prestige classes do not count towards uneven advancement.
If you DM really, seriously insists on this strange, strange houserule...
I looked through my tried and true builds and figured this'd work(modified for your ridiculous situation):
Human(if he'll let you use the "first class is favored class" ability)
bard7/paladin2/human paragon1/sublime chord2/human paragon2/paragnostic apostle3/human paragon 3/sublime chord3-4
Look how stupid that looks. Why can't you just play a powerful character without needing 2 hours of book work to work around his crazy rule?
I think that this would be the build to use. It's very versatile. It's powerful. It's durable. It's fairly easy to play. But, and here's the kicker, it's stupid complicated to flavour. That sounds bad, but honestly it's a good thing because it will be the ideal example of the problem that your DM is causing by enforcing his own vicious version of the xp penalty rule.
This isn't even as powerful as a wizard20, honestly.
if he won't let you use favored classes... idk... fighter2/barbarian2/half-orc paragon2/frenzied berzerker3
and then advance each base class i suppose. If he won't allow completed classes (half orc-paragon) to be discounted, then... try this build
[spoiler]wizard20[/spoiler]