I've done a bit of both, the longest-running campaign I'd really been in, had been very mundane, your typical join the local militia, train, train, train, beat up the bad guys, train, train, train, beat up every local monster or half-orc monster in the district, train, train, train. It was really quite mindless for me, and I didn't understand why people took so much joy and pleasure from defeating the half-orc/half dragon monstrosity that was suffering from arthritis.
So I wrote up my own campaign, modified 3rd edition with my own rules, and set out to look for players. *sigh* It took going to an online forum to even find enough people interested enough to get the action going. I'd get 1 or 2 in my area, we'd set a time, place, etc, and then they'd never show up. I DM'd there for about a year, and everytime a player came along and said, pretty, pretty please, it looks fun let me play! I'd take them in, etc. It got to the point where I had 15 players, and as I quickly found out, that'll burn out a DM faster than anything.
And really, I had a lot of fun DMing and comming up with separate adventures for each player, theyre were a lot of plots and twists and fun things to keep me entertained for hours comming up with the next big plot twist.
Then my newest boyfriend got me involved in his gaming group, I told him I'd DM'd for a year and was on DM Burn-out Vacation, and he was all impressed. I have to say, all that time I was DMing and playing as a player in the forums, had me thinking, okay, I'm a good role-player. However I quickly found out that isn't the case, because with real-time playing you have to think quickly, and in the forums I could and have literrally spent days looking at the problem, examining it from every angle, and then posting my best solution.
So I went in thinking: I'm a good role-player we'll all have lots of fun, even though I don't know much on the background or system.
Well.... now I've been playing it for 4 months, I'm currently thinking: What was I thinking? These guys are elitest advanced role-players! I constantly feel completely out-classed by the lot of them.
And how... how the hell did he come up with the idea to jump on the roof of the humvee perform a dc 35 balancing act while it was moving forward at 100 mph, and then when it hit a stationary red corvette, he does a forward flip, his feet gracefully touching the car's roof as he continues into a second forward flip, (making a performance check dc natural 20) which he by dumb luck absolutely makes, pulling out his rocket launcher, firing it twice, then putting it away, and quick drawing his machine gun, while landing on his feet?! The ghouls and vampires he was going to shoot, just stopped in their tracks and started applauding!
Never in my wildest dreams would I have even considered this! And it's like that all the time, but whenever I try anything remotely similiar with my characters, that character usually dies, or the current one which got critically injured and is going to be staying in the hospital for the next 4 games because I was trying something equally as stupid. Even though my character has a similiar dex modifier, and in game is a trapese swinger with more ranks in tumble and perform than the character that did the beforementioned backflip.
I feel woefully inadequate as a player most of the time when we all sit down and play together with that particular group, and I feel like I'm obligated to keep playing, because it's my boyfriend's group, and it's important to him that I continue to show up and play.

Although, it is a decent-sized group 3 players to 1 DM which is a lot better than the othe groups I'm in that have 9-14 players per 1 DM.
I was thinking of dropping out of those big group campaigns and doing Eberron Campaign setting, and luring 4 people away off to my own world, by running it the same day, different table which I think would make things easier for everyone involved. But then, I've never actually table-top DM'd before, so again I feel like a rank amature stepping into something that's probably going to be hard for me to do.