They aren't mutually exclusive.
Your list isn't frustrating because it wins easy or loses easy. It's frustrating because it's basically a 1.5 phase army. Foot of Gork and combat. Even movement is basically a non factor in an army like that.
You can have fun AND have a competitive list no problem. Hell, I think my Ogre list was fairly competitive. I was quite high in the rankings, massacred two armies, won another game and narrowly lost the other. But I and all my opponents had fun in every game. You can definitely go in with the attitude that you are going to play hard and win every game, but you don't need to play with attitude. You can still have fun, talk about the hobby, compliment the fella on his army. You never HAVE to take Foot if it just autowins you games. Take another spell instead. I don't think it's your army that's the problem, it's mindset. Winning and fun can happen at the same time. I tabled a guy in three turns and he gave me the vote for his favorite opponent because I was gracious in winning, offered to play him again even to waste time. Your foot of gork game was no fun for you because you cast a spell hoping it would smash a few units, knowing it does. Not trying to be offensive, but it\'s really Operator Error.
Basically, it's not the list that wins and loses games. It's the player. It's not the list that makes games fun or not. It's the player. Play your lists and just change the mindset behind them. Go to win tourneys, but beat their army, not them. Don't feel like you NEED to destroy everyone because it turns personal when you don't or do.
Look at your army and why it's boring. The above case? One phase and one spell army. Add other elements to your army so you are always playing in every phase.
Look at the specifics of your game and why it sucked. Foot beat everything and won the game. Don't always take Foot. You got obliterated in combat? Add a couple redirectors and chaff to pick fights instead of just assuming your giant blocks win every fight.
Look at your mindset. Why are fun and being really competitive not allowed to be inclusive?