AWS placement groups

I’ve decided to move my BP from home to the cloud. I’m looking for the lowest latency and high uptime (hence AWS) without jeopardizing the security of my BP.

So, I have several choices. First there’s talk about ‘availability zone’. I don’t know if this means a particular data center or several data centers.

What I’m looking for is low latency between my relay and BP and my relay and other relays. As far as my relay and BP go, I want to optimize low latency between the two without compromising security.

So I suppose I have the following options:

Set up relay and BP on the same machine.

Set up relay and BP in the same data center on separate physical machines.

Set up relay and BP in the same basic region but two different data centers in close proximity physically whether they are both AWS, or one is AWS and the other is GCP, for example.

Last option is set them far apart, but being that the relay needs to relay newly propagated transactions from the outside to the BP for processing doesn’t make this alternative sound competitive, but then again I don’t know what I’m doing - I have no background with server placements and how they affect intercommunication among them.

I was thinking of setting up the relay in the same data center as the BP, but the BP is on a separate machine, both running virtual instances.
I this a good idea or not, and if so, what AWS placement group strategy would I select for this placement: partition placement? Cluster placement allows for the lowest latency, but it sounds like it’s not suitable because each node is doing the same task from which there emerges one virtual computer/node consisting of many sub-nodes, and spread placement sounds like virtual instances running on the same underlying hardware.