Instead of plants you can do an asian arrangement with rocks and a water feature.

Two options for the meters:

With treated lumber, build out a pair walls, 6' - 8' tall and 14" - 16" deep -- one on each side of the meters -- resting the bottom of each of the walls on a pair of bricks to match the existing brick walk/edging or landscaping stones set on top of the ground. Attach a lattice gate/door to the walls in front of the meters.

Use the largest (widest) plastic flower pot (w/drain tray affixed) you can find or use rectangle pots. (w/drain tray affixed). Using treated wood, build a wood planter box (w/wheels) large enough for your pots plus an extra half inch deep. (Think deck spacing between the boards to enable drainage.) To the inside of the back of the wood planter box, affix a lattice ladder tall enough so that the lattice, resting on the inside of the bottom of the box, will be tall enough to cover both meters when the planter box is set in front of it. Plant ivy in the pots in the planter box and let it climb up the lattice.

Or do both.

While the meters are a bit unsightly, the heat pump is functional and not nearly as unsightly AND it needs room to breathe or it will not function properly. If you can scrape out an inch of soil and put small stones -- white or the smooth river stones -- over landscaping fabric to inhibit growth of weeds -- between the house and the existing brick edging/walk, rather than plant something in the soil that you'd need to dig to plant and/or tend or that requires mowing, and then put a row of flower pots on that stone all along the length of the brick edging/path, what you grow in the pots will be the focus of attention.

Note: An AC unit (or heat pump unit as well) will produce heat in summer as it removes heat from your home, so what you plant in the pots will need to be able to tolerate that and be kept watered as well as thrive in dappled sunlight. I have snake plants and wandering dew both tolerating similar conditions well.

You could also put a row of shrubs in front of that fence between the house and walk and, at least till they grow some height, add a pair of hooks and hanging baskets and/or wind chimes and/or bird feeder to draw attention away from the AC unit.

You could also add a bird bath in the most wide and open space -- sit it atop a grouping of bricks matching the sidewalk/edging you already have there.

I've had good success planting epimedium in dry shade. In my yard it grows well under a maple where nothing else has. I think it's beautiful. Give it a look.

Hi hkubo. It's been 6 years since you posted and I am curious on what you eventually did with the space?