Personally I switched from Tekin to Speed Passions and they have been superb for me. However, from the end of 2014 to 2015 their Customer Service was reportedly dropping the ball which is an area of concern for pretty much everyone. I bought a Hobbywing 3.1 and it is also excellent but I find has superior brakes, pretty much to any other ESC. I have an XR10 Justice in my 2WD RM car and the brakes are nice, but not as goos as that found on the 3.1.

The Toro TS120 is an excellent ESC and with Programming Box you're still under half of the cost of an RSX. Rick from crpplus.com runs them in all his cars and he's winning races consistently. The Toro seems to be made by Speed Passion as are a plethora of other ESC's from well established RC Brands, so it speaks to how good Speed Passion products are.

If you use a Sanwa Radio, their Vortex ESC's are definitely worth looking into because you can adjust settings on the fly via the radio, provided you have a corresponding receiver.

If you prefer to keep things consistent, just get another RSX if it works for you.