Just shoot how it feels good.I never shoot thinking of how
someone else will like my images.They are rarely cropped,but if they are I think another crop-compposition is possible
Great pictures can always be altered a little in size and composition.Sometimes I love a square..a panorama
Mediocre and just good pics..are harder to crop..thats my 2cents..

>How do you handle this dilemma?

You don't. When you print an 8X10 from a DSLR or 35mm, you're going to lose 1/6 of the frame. Compose accordingly. As an option, there are other sizes available from labs that use the Fujifilm "Frontier" printing system.

8x12... 1.5:1
10x15...1.5:1
Or for larger format printers, like the Ultrachrome Epsons,
12x18...1.5:1
16x24...1.5:1

Most labs charge the same amount for an 8x12 as an 8x10, and it's not much harder to find frames.

Yes, it's quite a dilemma. And don't even start with European standard frame sizes . . . :-)

Personally, I'm a full frame gal. I compose when I shoot. You don't mention what kind of clients you work with, but when I do portrait work, I'll print cropped or full frame depending on the client's request. It's their portrait afterall.

As for art prints, it's always full frame, and I'll do a custom mat. Really, if the print is truly a work of art, then custom matting or framing is a small investment. And besides, would a client tell a painter, "That's great, but can you do that in a 11x14 to fit my frame instead?" (Okay, some do say that, but it's rude.)

Then for commercial clients, ratio is basically irrelevant, since marketing will crop at will.

Just some general thoughts, but it's your work and your vision, so it's all about what you want your prints to be.

If you have access to tethered laptop or computer using Capture one software will solve your problem, by shooting directly to the puter, there are preset frame sizes which you are able to frame out with your subjects.