It's weird how so many players actually keep Lydia. Its almost like she is synonymous with the word follower. There are so many followers to pick and choose from, so why do people keep the first one they come across?
Personally I rarely use followers so I don't have much advice to give, but Erandur was a cool character and wasn't constantly kneeling when I used him (unlike the warrior followers). Maybe try a mage follower?
I think you're right, its not necessarily Lydia, its your first follower that people tend to keep with them. I picked up Faendal first, early in the game, and will probably finish the game with him. (I got him around level 5ish, and he was a welcome help because before I got him, I had to keep running away from the 3 mercenaries who kept killing me on sight). I also like how helpful and unassuming he is. While one companion always asked, "What do you want to take?" when I wanted to trade items, Faendal always offers to carry my stuff. "What do you want me to carry?"
I'm level 34 now, and he's still by my side. He tends to stay behind me and use his bow a lot, switching over to 2 handed longswords when enemies close on him. Unless its a boss he's fighting, I let him handle them himself and concentrate on the other enemies. I've only had to reload the game twice because he was killed - by a boss wraith and by a bandit chief.