I like KBOS and KJFK on the American Side, and CYYZ on the Canadian side for towers, but it does get a little boring hearing the same CTL, CFT rwy XX, etc.
If you like to hear oceanic clearances and position reports as well as a good mix of Center and APP traffic, the the CYYT or feed is great. So much different things happening that it does not get boring. A nice clear feed with lots of action. That along with flightaware gives a good overview of the traffic and of the cross atlantic traffic.