I'm a huge tonkatsu fan. I also religiously visited the Tonki location in Meguro circa 2005-2012. But, in my opinion, the vibe of the place was maybe a bit more special than the food itself. Here are some of my other favorites (where the food might be a step up from Tonki - YMMV).

Hasegawa - https://maps.app.goo.gl/jm3VTKdF2GNkY92Z6
To me, this is the perfect tonkatsu experience - no frills place, great pork, shredded cabbage, spicy mustard, miso, rice, tonkatsu sauce. All the elements come together in perfect harmony. I often make a special trip to the neighborhood to eat there.

Ichikatsu - https://maps.app.goo.gl/K5ULTW1qKFxN1ygb6
Same hood as Hasegawa (Ryogoku) and not quite as good, but still well worth a visit.

Marugo - https://maps.app.goo.gl/yWj2YqyosdyR24Vs9
Great spot in Akihabara - often has a long line, though.

Katsukami - https://maps.app.goo.gl/HLSLL9TU1TXzhnWY8
Fancier restaurant in Ginza serving a set course. Really great pork. Reservation required.

Musashiya - https://maps.app.goo.gl/JGTV5dgvz2C9gmNS9
Solid no frills tonkatsu in Shimbashi

Masamune - https://maps.app.goo.gl/bnUfK8MbFzmQukv2A
My fav tonkatsu in the Akasaka neighborhood