Using VMware Workstation have a lot of benefits, including:
- mobility: you can bring your lab in your bag to anywhere if running on laptop :-)
- simplicity: you don't need an different station to open vSphere Client and connect to your lab;
- recoverability: you can rebuild your environment very fast;
- no need "so" specific hardware: since you will install ESXi inside Workstation, you don't need to worry with physical NIC and disk controller compatibility... you will only need an compatible CPU and memory :-)
Using ESXi have some benefits, including:
- performance: will be better than running on Workstation;
- scalability: if not running in laptop, you can easily get more memory, disks and network cards than you will get on laptop.