I have a plastic one I reuse which usually surprises people. It is good quality though and has lasted me years.
For real trees, get a sustainably grown one. After Christmas find a tree recycling point. These are usually listed on your Local Authority website.
You can also rent trees from some places and they get replanted for next year! Or why not have a tree in a pot that you can reuse each year.
Whatever tree you have dispose of it responsibly.
Did you know LED lights use up to 90% less energy than standard bulbs? Consider using or switching to these. Some eco tree, bauble and light ideas to buy are below just click the images: