Recommended bluetooth dongles for BLE?

I’ve been prototyping my BLE communications with ble usb dongles by both Panda and Pluggable (both spec’ed at Bluetooth 4.0). I got to wondering earlier if all usb bluetooth dongles are roughly equal, or if some provide better throughput performance than other. Between the 2 types I have, there’s no real difference. In others’ experience, is that always the case? Or are there some that are better/recommended that others have had better luck with using bluez than others?

TIA