Have you reviewed the other FX-9590 running hot threads here? If not you might want to review them as there is a lot of useful information regarding cooling the FX-9590 CPUs. The first thing you should be sure of is that you are reading the CPU core temp, not the CPU socket temp which is displayed by many applets as "CPU Temp", when it's actually the CPU socket temp not the "core" temp. Showing the CPU socket temp as "CPU Temp" is a holdover from the days before CPUs had internal temp monitoring. There are a few applets that properly read AMD FX processors reasonable accurately in the 60-70C range. The applet Core Temp and HWinFO have been pretty good. Other apps can be completely wrong. None of the applets seem to be able to get the low temps ~10C or so, correct. You can even get negative numbers for ambient room temp CPU coolers.
I suspect you might be seeing the CPU socket temp because ~61C is the max user temp for the FX-8000 series CPUs and it's believe to apply to the FX-9000 series CPUs also. The CPUs have a built in thermal protection mechanism that lowers the CPU frequency at ~70C to prevent the CPU from getting so hot it can be damaged. At ~80C the CPU will shut down completely to prevent burn out. The AM3+ CPU socket used for the FX CPUs can read 10-25C hotter than the CPU core temp, depending on the load and duration because the socket has no active cooling like the CPU has. So be sure that you're reading "core" temp to start and work from there.
As far as which liquid cooler is "the best" this is often a matter of opinion for all practical purposes depending on your priorities and values. There are a number of test sites that review CPU coolers and they can show a comparison in thermal capacity, cost and performance. It's worth noting that both tower style HSF coolers as well as liquid coolers can properly cool any current AMD processor properly. The link below has a variety of HSF and liquid coolers that may help you determine what works best for you. Be sure to use the AMD reviews/data as CPU coolers perform slightly different on AMD sized CPUs vs. Intel.
A couple points regarding liquid coolers are in order. Most often the radiators require that outside air is blown across them and into the PC case - just the opposite of what you'd desire as it heats up the GPU, HDD, etc. Blowing hot air into the case from the radiators causes turbulence with your PC case fans that are trying discharging hot air out of the case. In addition it's always useful to have the heated air in the PC case exiting the back of the case with cool air entering the front (for most cases) to achieve good airflow properties. Some people also have issues with the OEM fans on liquid coolers being quite loud as the radiators require more static air pressure to efficiently cool the liquid. One final point on liquid coolers is that they introduce a coolant leak liability which is unfortunate but very real. These coolant leaks have caused mobo/GPU and other expensive component failures. It's best to understand the pros and cons of the different CPU coolers to determine which works best for your needs.
Are you sure the H100i is operating correctly? Those temperatures sound quite high for a water cooler.
What speed are the H100i fans running at? Depending on how you setup your H100i there are three fan profiles, silent, balanced and high performance.