Paddles are definitely easier to remove. If you open carry, a paddle holster may be a good choice. I don't think they're particularly easy to put on...of course, they don't require removal of your belt, as a belt slide holster would.
Pancake (belt slide) holsters hold the firearm closer to the body thus making this a better choice for concealled carry (assuming the covering garment is a shirt).
I've read that paddle holsters can be grabbed and removed by an attacker. Well, I know the paddle holster I had (for a large frame Taurus .357 revolver) couldn't be easily grabbed or removed by an assailant (unless one is totally unaware of his or her surroundings, i.e. braindead). I've also heard comments about paddle holsters being uncomfortable..but mine was quite comfortable.
I no longer have a paddle holster, but I do own a few belt slide holsters. If you do go for a paddle holster, buy a quality one...not a $19.95 POS. Be prepared to open carry or print if you wear in under a drapped shirt.