Tor is as anonymous as the end user makes it, and despite it being a pretty good out of the box solution it itself is susceptible to attacks, and if we are relying on what effectively is a third party program to run a Bitcoin node, any outages or vulnerabilities would have the chance of knocking out all Bitcoin nodes for a period of time, which is definitely not great for Bitcoin in general.

I think in the long run it would make sense for Bitcoin to inherently support transaction propagation privacy, without relying on external solutions. The more people use such a system, the better it can ensure privacy. High usage can only be ensured by making it part of Bitcoin.

With Tor (I'm not super familiar with the others), you could potentially correlate multiple transactions to the same node. AFAIK, with Dandelion, a new circuit is chosen for each broadcast, so it is much harder to correlate multiple transactions. Also, as mentioned earlier, it would be better for Bitcoin to adopt its own privacy protocols rather than relying on external ones. If the privacy protocol was built into the network protocol itself, that would be better than just a few people choosing to use an external privacy method.