Hey there Alli,
Thanks for finding the community and posting the question! I’m a Particle employee so am obviously biased, but would be happy to give you some honest information to help you make the best choice for your project.
On the hardware side, if bluetooth is a requirement, the Photon probably isn’t the best tool for this job. I’d recommend one of two other options from our hardware portfolio that meet your criteria of Wi-Fi + Bluetooth (making it comparable to the ESP32):
The RedBear Duo. The Duo is a Wi-Fi + BLE product that is one of our “compounds”, meaning it was produced by a third party company (RedBear) but still works with all of Particle’s software services (which I’ll discuss below). We loved RedBear product’s so much we actually acquired them – it’s a great product that will likely serve your needs today.
The Argon. The Argon is one of the hardware products from our new Particle Mesh portfolio that is in many ways a successor to the Photon and to the RedBear Duo. It isn’t available until October, but includes some awesome features like Adafruit Feather form factor as well as Wi-Fi / Mesh / Bluetooth 5 (longer range, higher bandwidth) connectivity. You could use BT5 to connect your peripheral sensors, or you could use the included Mesh radio, which is going to be more robust than Bluetooth for connecting your wireless sensors.
As similar or different as the hardware solutions are, however, the real difference between the Photon and the ESP32 is the software that comes with the Photon (and all other Particle development kits).
Whereas the ESP32 is a piece of hardware, the Photon is an entire IoT development platform that includes integrated development tools for writing code, a pre-integrated Cloud for messaging and security, out of the box OTA firmware updates, complete reference documentation and learning examples, and a web based IDE.
On top of all of that, we’ve got one of the largest and most helpful developer communities in the game, so if and when you hit a snag there are tons of individuals who would be happy to contribute their knowledge to get you back up and running.
Again, a biased opinion, but I hope it helps you as you make your decision! The ESP32 is definitely a powerful piece of hardware, but in our experience building connected products is so much more about the full set of tools that you have at your disposal (hardware, firmware, software, information) and less about the nitty-gritty specs of the hardware.