Dark Horse and Image have some great titles, but none I really read often enough to be my favorite. I was always into Marvel as a kid, and grew up with Spider-man and X-men, never really understanding most of the DC Heros. But now I'm catching up on all the cool DC stuff I missed. They really do take different approaches. Marvel goes with the really "human" heroes, when Stan Lee made all their personal lives just as interesting as their super lives. DC goes the complete opposite, having God-like heroes like old Olympus, which is also pretty cool if written correctly. Normally, I'd choose Marvel, but I hardly pick up any Marvel book nowadays (Everything's Secret Invasion...and I'm just not into that...) so I'll have to give the nod to DC...for now...
Way to quote Stan the Man, Moo2u !
I am torn...because I've went through exactly what you described. I grew up with Marvel comics, and my favorite superhero will always be Spider-Man. Not for his backstory and relatability (I developped that as I grew up), but for three specific reasons deeply rooted in my childhood impression of the character. First off, he's a smartass and he loves to taunt his ennemies. I loved how infuriated the villains got as Spidey kept wisecracking, even when they had him on the ropes. Second, he swung on a thread and stuck on walls, which I thought was really amazing. And thirdly, he had a really distinctive costume, with giant eyes and a full face mask. I also loved the X-Men and Moon Knight, which were my other two favorites. I still have those cheap translated comics my mom bought in flea markets. For this reason, Marvel sticks close to my heart. I recently read the main Civil War storyline, which I thought was an amazing piece of comic book writing...Marvel has such a great stable of heroes, it's hard not to give it any credit.
And yet, nowadays, I find myself drawn to the DC heroes...especially since they have this kind of ''grandeur'' about them, just as you described. I loved Batman because of the TV series, the Animated series and the movies, but I slowly rediscovered Superman, Captain Marvel, Flash, Green Arrow the whole Justice League. As an historian, I love old stuff, and DC is the stuff from which comic book history is made. I ate up great books like Superman : Red Son, Death and return of Superman, Kingdom Come, The Dark Knight Returns, The Killing Joke, Batman Year One, The Long Halloween, etc. I am also reading some old Golden Age stuff...this really makes you understand how far comics have gone since the 30s. I have heard bad things about Countdown, which is a shame since 52 was great. I wonder if Final Crisis will be any good...Infinite Crisis felt like beating a dead horse, and it makes little sense to me why they would unmake the continuity they tried to build so hard with Crisis on Infinite Earth, but I digress. Secret Invasion seems more interesting, but since I am in the process of discovering all it has to offer, DC gets my vote, not for the current stuff, but for all the great TPBs I have yet to read (like Superman : Birthright or Some Green Arrow/Green Lantern).