Enlarger selection also depends on the space you have.
- If you have to break down the enlarger and store it, that really limits you. Many enlargers do not breakdown and store easily.
- My Durst M-600 (6x6 format) breaks down and stores in a square box, half the size of the LONG rectangle box of my Omega C-67 (6x7 format). My nephew's Durst F-30 (35mm format) fits into an even smaller box than my M-600.
- Many used enlargers are without boxes, so you would have to make your own storage box.
- Some enlargers are easy to assemble, then break down and store.
- Whereas others are NOT easy to assemble and breakdown. They are meant to be setup and left up.
- If you can leave the enlarger on a cart, to wheel out of the way, you just need an enlarger and cart that match up in size.
- If the enlarger is permanent, then anything goes, as long as it fits.
- If you are very space constrained, you may be backed into a small enlarger (35mm), like the Durst F-30. But with imagination, you can do a 6x6 enlarger. I use my M-600 in a "small" half bath.
I started with a Durst M-600, a 6x6 enlarger. That worked well for MANY years, as I did not go beyond 6x6. And it is easily storeable, #1.
I recently got a Durst L-1000, a 4x5 enlarger, so that I could print 4x5 negatives (any anything smaller). The L-1000 is NOT storeable, once set up it stays up, so #2 or preferably #3.
Given the low cost of used enlargers today, I would do what SG said. Get an enlarger for a format as big as you can think you may use, then to up again, maybe up to 4x5. The logic is that a 4x5 enlarger takes up only a little more space than a 6x7 enlarger, but you don't have to buy another enlarger later if you go beyond 35mm or 6x6, you already have it.