Load Balancer is simple to create and well integrate with other Azure resources such as Scale Set, Web App and it provides almost feature we need with layer 4 Load balancer: Destination selection, Port forwarding, Automatic reconfiguration, Health probes...
We could use the Basic SKU for free and it has all the features we need for small or medium applications
Documentation is not clear enough and configures health probes base on backend service in the portal is confusing
Use this Basic Sku unless you have special requirement, it only works in layer 4 so if you need other feature such as HTTP header or client certificate you need to use Application Gateway
We create VM scale set with Load Balancer and it works well. It supports scale up and down, distribute traffic to all VM in scale set and we do not need to care about VM scale set just Load Balancer
Load Balancer provides good build in metric and Resource health report to troubleshoot issue