It depends on the camera. Neither my compact nor my µ4/3 has an EVF, therefore I have no other choice than using the screen. I like to compose like that, but in bright sunlight I'd prefer either an EVF or an OVF. When I take photographs with my DSLR, which I have done extremely seldom during the last months, I compose with the OVF exclusively.
First off. I'm proud you figured this out. Thanks for your continuous positive energy on the forum.
I prefer the screen. Here's why.
Photographs are 2 dimensional.
Viewing on the screen lends to the abstraction of the 3rd dimension. You are viewing your image upon capture.
The other good thing is that the screen allows you to see the elements outside the frame.
Pictor and Don have already posted good points. I like Don's observation about the LCD eliminating the 3 dimensional element and the wider picture - I just wish I had better closeup vision. With my E-PL1, I almost exclusively use the EVF, although if I am inside I have used the LCD. With another camera I have I tend to use the LCD initially but then look through the optical viewfinder....I'm working on that one.
EVF. Which ever is available to me. I wish I had the G2 EVF on my GF1, but I'll take what I can get. Two things: it keeps me focused and it helps keep my shots steady. A bonus on the GF1 is it saves on battery life =)
Sometimes using the LCD is nice though, I can evaluate the entire scene *outside* the FOV and play. But that's rare for me, not a preference.
On a DSLR, OVF all the way, it just doesn't feel natural any other way (except when doing stationary macro work, which is almost never, heh)
Exactly - when there's more than one option, I tend to use them depending on circumstances. On my ep2 (and on the epl1 before that) I tend to use the LCD when possible, which is mostly. But when the sun is just too bright to really see the LCD or sometimes when I'm shooting with a long lens and need that extra little bit of stability, I shoot with the evf. They both work and are both "best" under the right circumstances.