We need to decide on the best and easy option to collect all kinds of windows event logs
The answer is the same for non-cloud users and those who don't have ES. Install a universal forwarder on each Windows server then enable the inputs for the desired logs.
installing a universal forwarder on each windows doesn't seem feasible here. Can we use WMI instead. If yes, i suppose there are limitations on the types of logs that can be collected (no registry logs, AD logs etc). Please correct me if I am wrong
Yes, WMI is an option, but not a good one. WMI will affect the target server's performance more than a forwarder will.