It really depends on your use case and what you want to do with your logs.
Vector is an ETL tool that is more an alternative for Logstash, it has many source, transforms and sinks that you can use to collect logs and send them to Elasticsearch.
It is not an alternative for Elastic Agent because Elastic Agent is not just a log collector, Elastic Agent has many integrations that will use ingest pipelines to parse your data and will make it easier to get useful information from your logs, you do not have to worry about building pipelines to parse your message and you will be able to use the built-in dashboards and alert rules when you use some integration.
You do not have an easier alternative to Elastic Agent, the alternative is to create your own parsers, your own dashboards and your own alert rules and sometimes this can be a lot of work.
Basically using the Elastic Agent you just need to add the integration you want to get your logs, without the Elastic Agent you need to manage everything, the pipeline to parse your data, the index template, the index lifecycle policy, the dashboards, the alert rules etc.
Thanks @leandrojmp , as usual your response is very accurate and useful.
In some cases, I have systems that are producing massive quantities of logs.
In those cases I have seen Elastic-Agent 8.4.2 become a zombie process
and sometimes elastic-agent uses so much CPU that it starves other components on the system.
I have upgraded my system to to Elastic 8.9.0 and my agents to Elastic-Agent 8.9.0, so hopefully
the problems I saw with 8.4.2 are gone.
But at the same time I am looking at alternatives to elastic-agent for shipping logs to Elasticsearch.
I may be able to live without some of the features like custom pipelines and integrations for this particular use case.