It depends on whether you feel indifferent, advantaged, or disadvantaged by a "close fit."
The easiest thing to recommend here is the ThermalRight XP-90 or (better) XP-90C. There are probably other coolers fitting that profile and footprint, but the load temperatures will be higher. It may actually be the case that the CNPS-9500-LED would fit better than the ThermalRight XP-120 (or SI-120 -- better), but not quite as well as the XP90 /C. I'd say for cooling without consideration to the noise, the rank order would follow this way, from best to worst:
ThermalRight SI-120
CNPS-9500-LED
ThermalRight XP120 and ThermalRight XP90C
ThermalRight XP90
CNPS-7700-Cu
CNPS-7000-Cu
For noise, it's just a matter of turning down the fans and living with a slightly higher thermal resistance at CPU idle, and if you can control the fan thermally so they spin up to just the required rpm and CFM to get thermal resistance to minimum, it then boils down to choice of a fan. With the Zalman coolers, you don't have much choice because you take what they give you unless you can "mod" the cooler for a replacement.
As consequence of a "heated discussion" on this forum, I experimented today with my Delta Tri-Blade 120x38mm CPU fan. I usually have it running at close to 2,500rpm in a closed case. It was a rather cool morning -- about 70F -- but I tuned down the fan speed to around 1,800 rpm. I could tune it down farther, per Citarella's article on the SI-120 and his bench-test results -- to about 1,000. But the IDLE temperature didn't increase at all. Since it spins up to a preset speed when temperature rises toward load past a threshold of 40C, the only difference with the low rpms would seem to be chipset and memory cooling. But guess what? With the thermal sensor on the chipset heatsink monitoring temps there, it also barely changed at all when I tuned down the CPU fan!
The ThermalRight 120 models will distribute air on motherboard parts, reducing or eliminating the need to buy things like "DDR-cooler-fans" and "chipset-heatsink-fans." They will also distribute air across the back of your AGP or PCI-E card. If they fit without touching the graphics adapter (very important to avoid short circuits), the only drawback is the occasional need to access the motherboard "from above." I've discovered that for many things I can access part of the covered area from the other (less used) case panel, approaching from "below" the XP120. And it isn't the XP120 that makes it difficult to access my memory modules: it's the graphics adapter, which must be removed.
