Hmmm tough question there. I too love Webers for their versatility, and always say if I cold only have one cooker it'd prolly be a kettle. However I own both so I never really thought about which one would win out in a contest. Honestly I like the Akorn for it's own uniqueness and the flavor it imparts with burning lump, and it's ridiculously efficient too. I don't really smoke in my Akorn since I have an UDS, and a horizontal drum smoker, and I don't want everything I cook on the Akorn to taste like smoke like it will if it's used as a smoker(when the smoke seasoning burns off while grilling). I look at it more as a grill/roaster that has it's own application and flavor characteristics(see lump coal). On the other hand, you mentioned ash buildup in your Weber; have you considered using lump in your kettle instead of briqs? I've found there's prolly 1/10 the ash buildup with lump vs. briqs. The Performer does have some nice features like a table etc., but the Akorn also have shelves, extra cook rack etc. plus a cast iron grate is an awesome feature to have standard. You can also make a "one touch mod" to start your coals if you're a little handy with a torch and solder. If I get a chance I'll post a pic of this mod.
They're both great cookers...
Guess after all that blathering I can't really answer your question, but if you're keeping your kettle and adding to the "family" I'd say get an Akorn. That's just my opinion, man.
UDS, Akorn, Weber Red Head Kettle, Drum Grill, Gasser w/cobwebs all over it. I'm JD.