if you had the choice which GPU quadpro k2000 or quadpro 5000 would be better for AE / Premiere ??

Neither GPU is supported any more in the newest versions of Premiere Pro.

And the Quadro 5000 is now completely obsolete, as Nvidia itself had terminated all driver support outside of archived drivers for all Fermi GPUs in 2018. And the newest versions of Premiere Pro now require a driver version that has a CUDA version that no longer supports the Quadro K2000 any more (as in, the newer Quadro display drivers will install, but CUDA will be completely disabled unless you have a much newer GPU). The GPU architecture that was used in the Quadro 5000 dates way back to 2010 (with the GPU itself released in February 2011), while the Quadro K2000 dates from early 2013 using technology that dated back to mid-2012. Adobe is now no longer supporting hardware that's more than four to five years old any more. But the newer of the two GPUs is now more than eight years old now.

That said, you can try running Premiere Pro, but you will not have any GPU acceleration at all as the MPE renderer will be effectively locked to the software-only mode.

And forget about trying to install an older version of Premiere Pro: The most recent version that supported the Quadro 5000, Premiere Pro CC 2018 (12.x), is now no longer officially available any more. And for the Quadro K2000, you must resort to installing a version between 13.1.5 (the oldest version that is still available as of November 2020) and 14.1 in order to work properly, and you must install a driver version that's in the 43x.xx series (as beginning with driver version 44x.xx, CUDA support for first-gen Kepler GPUs began to become depreciated, and eliminated entirely in the 45x.xx drivers).

And even with all that, don't expect much if any GPU acceleration out of that Quadro K2000: That GPU has only 384 CUDA cores, and a memory throughput of only 64 GB/s via its 128-bit GDDR5 memory bus. (For comparison, the Quadro 5000 has only 352 CUDA cores and a memory throughput of only 120 GB/s despite its 320-bit GDDR5 memory bus, and from my previous experiences with Fermi it cannot do 4k well at all and is limited to a maximum display and processing resolution of only 2560x1440 as such GPUs are too weak to utilize the high at the time memory throughput despite consuming a very high amount of electrical power.) A far cry from today's budget GeForce GTX 1650 Super, with its 1,280 CUDA cores and a memory throughput of 192 GB/s (with its 128-bit GDDR6 memory bus).

The one thing that really stands out is the k200 has a 441MHz faster GPU clock speed then the 5000, this has to effect the rendering process right?