Hamburgler has some more tokyo burgers for you:
So heres the thing (and yes, I have only had three burgers in Tokyo). It would seem that what Americans consider a hamburger patty wouldn't be considered a hamburger patty here (and its not fair too say because I have only eaten fast food and chain restaurant burgers in Tokyo), but the trend is that the burger patty is more like a sausage patty in look, texture, and taste, sans the sausage seasoning. So its all about how you dress it up. Freshness burger dresses it up well, and 380 yen (probably around 4.10 USD) it does the job.
Still sticking with Mos Burger though.