In a couple weeks from now, Monero will start using the RandomX PoW algorithm, replacing the current Cryptonight-R. What are the current pool miner software that may be used to mine with this particular algorithm, so that a current miner may use to continue mining after the switch ?
XMRig is the miner with the most actively developed RandomX implementation. It can also seamlessly switch from CN/R to RandomX when the network updates if in your pool config you set the property
"coin": "monero". Aside from mining to a pool with XMRig, you can also solo mine against your Monero daemon. This offers a performance improvement over simply mining directly with the daemon's built-in miner.
There is also a version of xmr-stak for RandomX mining, though it should be noted, they simply copied the RandomX code directly from XMRig. Whether this miner supports automatic switching from CN/R or whether the developers plan any unique features w.r.t. RandomX, I cannot answer.