What's the BLE Range?
I just want to know on what the BLE range depends on other than the following :


just from the top of my head (and assuming BLE doesn't use MIMO):


Antennas (not all antennas are equally efficient at converting current to radio waves or vice versa. Also, antennas work better in one spatial direction than into others)
transmission losses and mismatch losses on-PCB
Large-scale fading / shadowing and path loss coefficients (so, this is "objects between transmitter and receivers, also, energy spreads out on a sphere hull, so the further you are away from a transmitter, the less you get")
Small Scale Fading / multipath self-interference, which can lead to frequency selectiveness, implying coherence bandwidth relative to signal bandwidth (so, this is, objects that your signal can bounce off)
Interferers (Other devices using the same band)


Especially, the power
how much of the time these are transmitting, 
how well they notice your BLE transmissions and keep silent while you use the medium
kind of interfering device as well as
where the interferers are located. See: Hidden Station Problem

Temperature, and hence noise figure of the receive amplifier (hotter amplifier = more noise = less sensitivity = less range)
Stationarity of the channel (i.e. are reflectors or transmitters or receivers moving), meaning coherence time relative to transmission time (things move, suddenly the signal paths that used to sum up  to work very well sum up to cancel out, and you receive nothing)
broadband impulse noise, as caused by sparks and other transient phenomena (especially: welding)
Oscillator stability, which essentially goes into stationarity of the channel (Imagine talking to someone who's using autotune all the time, but is also constantly turning the knob on the target tune)



  Does having a lot of other BLE / Bluetooth / WiFi around affect my range?


Yes. In dense networks, we often find the ability of devices to communicate to be dominated by interference, not by noise or other phenomena.

That is the reason that in inner cities, although phones and base stations get more sensitive every year, the mobile phone cells are getting smaller instead of bigger. When you have a smaller cell, you have fewer devices to coordinate, there's more per-device usable spectrum. Bluetooth is uncoordinated, so in a dense, large network, you'll run into a situation where most transmissions fail. Large range isn't always a good thing, because it means that you disturb more neighbors, and more neighbors disturb you.

As a matter of fact, I was talking just a week ago to someone doing simulations of exactly that, BLE transmitters in densely packed environments, and found that you relatively soon run into that problem when you assume a few devices per square meter, although the reach of the "isolated" device-to-device was plenty enough to cover a large hall, aside from very few hidden spots.

So, sorry. Anything short of an extremely high-effort simulation of the environment AND the device won't give you exact numbers. There's tools for WiFi planners that show approximate maps for signal quality in a room (you'd need to feed in position of the access point and the geometry of the room), but they of course don't know about other devices using the same frequency band.

Considering the fact that device orientation (i.e. in which direction does the antenna point, in which directions is the rest of the device "in its own way") can easily contribute several dB of attenuation, which means you can easily get something like "works for 50m if it stands like this, but if you turn it by 30°, it only reaches 5m", I'd really not care too much about a range figure of a chip. You'll need to build and test your complete system.