Let's cut right to the chase. I'm not gonna boldly state what size camera or sensor or film size is the best. Photography is all about preferences and compromises and this choice is no different. What I will do is discuss the variety of formats that I've used and share some of my experiences, thoughts and biases.
We'll start from small and work our way up.
iPhone (1/3" Sensor Size)
(4.8mm x 3.5mm & Crop Factor of 7.2)
I'm relatively new to phone photography but I confess that they are handy little devices. I mostly use my phone as a scouting and planning camera. But that said, they can create wonderful images when you don't push them beyond their limits.
The downside is the small sensors and low megapixel count in phones. I tend to shoot scenes with ample light to reduce the noise associated with these types of sensors. In addition I use the built in panorama feature whenever possible to either increases my field of view or to increase my effective megapixel count.
Current Choice: iPhone SE - I like its small size and pocketablility.
I’ve also used: Samsung Galaxy S7
DJI Drones (1/2.3" Sensor Size)
(6.2mm x 4.6mm & a Crop Factor of 5.6)
I've used a whole line of DJI drones (P1, P2, P3 Pro & Mavic Pro) that had this, or a similar, sensor and they shares many of the same characteristics as the phone sized sensors. Namely that you really don't want to push them past thier limits for best results. So I use the same formula as I do with my phone: good light and stitched panoramas.
And although the quality of the images from small drone cameras requires a bit of care and planning, the results can often be amazing. So they are definitely worth tweaking for all they’re worth.
Current Choice: DJI Mavic Pro - The Mavic is the best choice I’ve yet experienced for my commercial / real estate work. It’s easy to transport and set up so I’m able to offer my clients aerial photos at the same rate as I charge for my other images.
I’ve also used: DJI Phantom P1, P2, and P3 Pro
APS-C (Crop Sensor)
(23.6mm x 15.7mm & Crop Factor of 1.5)
I’ve had a number of APS-C cameras including Fujifilm X-E1 & X-T1, Sony a6000 & a6300 and Sigma DP1 & DP3 Merrill. And Fujifilm is the camera system that I recommend most to folks who ask what camera should I buy.
I feel that APC-C is the sweet spot between quality, price and size. And even though I currently shoot full frame for my commercial jobs and medium format film and digital for my landscape work, I still have a little X70 for my walk around / scouting camera. And the quality and fun of shooting that little camera continues to amaze me.
Current Choice: Fujifilm X70 - My fun, amazingly portable “point and shoot” scouting camera which often captures “Keepers”. This is a pretty versatile camera as it also serves as my backup Real Estate Photography camera.
I’ve also used: Fujifilm X-E1, X-T1, X70, X100, X100S, X100T, Sigma Merrill DP1 & DP3 and the Sony a6300.
(36mm x 24mm & Crop Factor of 1)
A full frame Sony A7Rii is my “workhorse” camera. And the high megapixel sensor and exceptional dynamic range are real assets in my interior real estate photography. And although I confess that I don’t get much joy shooting Sony cameras, I can’t deny that they have leading edge technology that offers a number of compelling advantages.
Current Choice: Sony A7Rii
I’ve also used: Canon EOS 6D, Leica M9, Sony Alpha a7R, a7Rii & Sony Cyber-Shot RX1R and a Nikon D40.
(65mm x 24mm & Crop Factor of 1)
I had a short relationship with this amazing 35mm panoramic film camera. And if it wasn't for my fondness for medium format, I might still be using this iconic camera. The Xpan is a panorama camera that produces a 24 x 65mm which can capture a sweet and very unique perspective.
Current Choice: No Longer Using - Currently my preference for film photography is the 2 1/4 inch square format
Medium Format 2 1/4 Film
(56mm x 56mm)
For my landscape work I’m always juggling capturing the highest quality image while being able to carry my gear to the location I want to photograph. This effort is one of the more difficult challenges I find in location photography. Which is why I'm currently really enjoying shooting with my Mamiya 6. This is a pretty sweet 6x6 range finder system that has three available lenses (50mm, 75mm & 150mm). While some might consider the lens selection limiting, I find having just a few lightweight choices liberating in their simplicity.
In addition to the stunning, and relatively large negatives, I'm loving the 6x6 square format. It's another aspect ratio that can be a bit of an effort to find compelling compositions, but I've never really bonded with the 35mm 2x3 aspect ratio so I'm enjoying the challenge.
Current Choice: Mamiya 6
I’ve also used: Hasselblad 203FE, 500CM and Hasselblad Flexbody.
I strongly believe that the choice of camera, and sensor size, is a very personal and subjective choice. Some folks treat camera gear as a religious mission, but as you might have guessed by now, I've visit a number of photographic churches. A sane person my wonder why? What difference does it make? Take the image and move on. But for me the camera is a tool, but also a creative part of the process. And a well made, inspiring tool, makes a huge difference to me when I shoot.
But the ultimate take-away from all this is that if you find a camera that inspires you to shoot you will come home with compelling images.