I have the foam insert type that Lowes sells. The pine needles still build up on top, but don't restrict the water flow. The needles are easy to brush off, but it still means you have to get up close to them to remove the unslightlyness. They could pose a problem with ice damming, I guess, but that is not a problem here in Wayne county. I don't know if a leaf blower attachment would work because I have not tried that.
I have tried the expanded metal mesh type before, but the needles just ended up getting stuck in the mesh. Water still flowed better, but they were difficult to clean out. My sister had them on her house, but the small leaves matted on them and the water just overflowed off the side instead of going through the gutter. She did not have long needle pines. Inexpensive, but I would not recommend them.
I have not tried the fine mesh or wrap-around types. With about 100' of gutters, that is a bit out of my price range.