IDA is a Windows, Linux or Mac OS X hosted multi-processor disassembler and debugger that offers so many features it is hard to describe them all. Just grab an evaluation version if you want a test drive.
The most important and obvious difference between TTD and rr is that TTD is for Windows and rr is for Linux (though a few crazy people have had success debugging Windows applications in Wine under rr).
TTD supports recording of multiple threads in parallel, while rr is limited to a single core.
On the other hand, per-thread recording overhead seems to be much higher in TTD than in rr. It's hard to make a direct comparison, but a simple "start Firefox, display mozilla.org, shut down" test run on similar hardware takes about 250 seconds under TTD and 26 seconds under rr.
Browser-based frontend to gdb (gnu debugger). Add breakpoints, view the stack, visualize data structures, and more in C, C++, Go, Rust, and Fortran. Run gdbgui from the terminal and a new tab will open in your browser.