You can only shoot one format for the rest of your life
What is it?
110? 35? 120? 4x5? 8x10? I know there are plenty more but I'm curious to hear what you would stick with it it could only be one and why it would be that.
Myself? 35mm. Cameras are everywhere and many of practically free. Film is generally the most cost effective and you can print up to 11x14 pretty easily. You just need to pick a slower film and a low grain developer. There is also a wide variety of camras, and in each sub-genre there are really stellar examples. You aren't just limited to a few gems of the bunch. Not to mention you can shoot it half frame (Pen F) or double frame (X-pan) and even use swing lens cameras for different pnaorama effects. Let's not even get into the lomography cameras and the options they provide.
I want to say 6x6 but you're probably right about 35mm.
If I haven't said it 1000 times already, 8x10 is the perfect format, IMO. It's slow, contemplative, contact prints nicely, enlarges like a boss, and so long as my freezer doesn't explode, I'm set shooting it for the next couple of years anyway. If the day comes where I can no longer stock pile color negative film, I'll simply filter 3 sheets of B&W and make trichomies. If B&W ever goes away, I'll shoot wet plates. Should paper somehow also disappear, I can already coat my own papers via traditional silver and non-silver methods.
The only real problem will be staying in good enough shape over the years with the big 'ole camera to still be using it into my 60's, 70's, and beyond.
If I were absolutely forced to choose, it would be 35mm. When enlarging, you can get either really grainy or really smooth images, depending on your film and developer. Also, the cameras are freakin' awesome.
6x6 has even cooler cameras (Hassy, TLR's) and enlarges even more beautifully, but you're limited to 12-exposure rolls and can't get a nice grainy image like you can on, say Tri-X.
Oh well...
I would have to go with 120 format. Simply because it's one of the more versatile formats out there, 6x4.5, 6x6, 6x7, 6x9...and even more. Plus you have every camera under the sun out there, from TLRs, to Point and Shoots, SLRs...and having some of the best glass out there to shoot through.
Sure you're limited to the number of shots per roll, but maybe that's a good thing.
120: Versatile and fairly compact. Yet very good results, technically. Tempted to say 135 as I like my Leica a lot, but 120 wins the day, I shoot mostly 6x6, but can do 6x7, 6x8, 6x9, 6x12 and 6x17. Hard to beat.
to be honest i would choose polaroid sx-70 if i could only choose one.
ok, i dont have any sx-70 cameras but just think about it for a minute. a FOLDING slr camera, all automatic (auto exposure, auto wind and on some models autofocus), you get to see your picture soon after you take it, the photo is big and watching it develop is fun
you get my handle?
Idon't care what format it is, as long as I have film to shoot the rest of my life!
or 9x6 for those across the pond
Polaroid Type 100 (peel film)
Yes!
...until I read all of the good arguments for 35mm. :)
I'd go with 35mm for all the reasons stated at the beginning.
I'm glad we don't have to choose just one. I've never got into 120, but I'd like to. It's intriguing and versatile.
I had to laugh at the suggestion of Polaroid SX70. The camera and film are amazing feats of technology and engineering, and it's definitely a cool thing to have, but... No.
110 gets my vote for most worthless. No, wait... I almost forgot about Disc film! But 110 is pretty weak, anyhow.
Hey man, easy on the format bashing - "110 gets my vote for most worthless"
Just because it's not for you doesn't mean it's not without merit. Viva 110.

Where's the grain? 110 can hold its own.
OK, I'll admit my experience with 110 was limited to mostly toy-like and semi-disposable cameras, certainly nothing like the Pentax Auto 110, and that has probably biased me against 110 film.
Then again, the limited choice of equipment for 110 could be considered a valid knock against it too, so I dunno.
4x5. Simply because I don't have an 8x10 :)
it's slow, the quality of the image is better than anything out there, other than anything larger, and you can get 2 4x5 frames per 8x10 frame (s0 X-Ray film goes further). Paper negatives, something that you can't do with 35mm.. (at least not very easily).
Yeah, definitely 4x5...
But since that is not the case, I'll shot anything I can get... I'm not for 110, because it's not my shooting style, but if someone gave me a 110 camera with film, I'd use it..


35mm for the compactness and the quality of the images, definitively.