There are a few pieces of information that would really help.

The first is: how high are the lines? You really, really want to pick something that will not get near the lines, since the power company will come over and deal with anything that gets close - in a way that will not make you happy.

Second, for privacy, how much height do you need? Are there 2nd story windows overlooking your yard that you'd like to block, or just people occasionally and inadvertently peeking over the top of the fence?

The best way to determine the height you need is to send friend or spouse out there to walk along the line where you intend to plant, holding a 2 x 4 upright. If the 2x4 is 10' tall, you use that to judge what 20' would do for you, vs whether 15' would work. If you want to make this really accurate, you can take a notebook with you, and every time your helper moves you move 3 or 4 times, so you get a matrix showing how much height gives you line-of-sight blocking in the different parts of your yard where you particularly want privacy.

The maples may be growing right next to the fence; don't try to grow anything else closer than about 5', or about the height of the fence. I learned this the hard, slow way, after trying several different screening plants along a stockade fence; they were all planted to close to the fence and none of them did well. It cost me several years o waiting for things to fill in, and if I'd started out 20 years ago placing my first row of narrow junipers correctly, I'd probably have had a nice screen for about 15 years ow, instead of STILL being at a stage of waiting for things to fill in.

Oops! Last question: do you think evergreen screening is important, or will you be satisfied with seasonal leaves? There are some shrubby deciduous trees that are pretty effective even when out of leaf, others (like magnolia virginiana) that give no privacy at all after the leaves fall.