Artificial Christmas trees are almost always 50% off everywhere, so don't buy one unless it's on sale!
There are so many different 'species' of trees to choose from. I prefer the Fir/Spruce trees. Mine is about 9 years old and is a Blue Dunhill Fir from Shopko. I like the beauty of the bluish green trees which is why I chose that one. You may prefer a different type or different color tone.
I highly recommend purchasing an
UNLIT tree! If you really want the convenience of not having to put lights on every year, fine, but only expect them to last a few years. I always read about people having sections of lights that won't work anymore and the lights are almost impossible to remove on the prelit trees. With an unlit tree you are also free to change up the lights whenever you want...maybe one year you want white, and the next year multi.
They now make artificial trees with molded plastic tips which make them look even more realistic. Some have a combination of the old-style and the new molded tips. They're really beautiful...usually more expensive, but worth it in my opinion for a tree you'll have 20 years.
Also consider whether or not you want a tree that comes in just a few sections, or one that has individual branches you hook in. Mine has individual branches and it's a process to assemble it (and bend all of the tips so they look natural) but I grew up having a tree just like that so I'm used to the labor involved. My parents purchased a prelit tree at Costco last year that comes in just 3 or 4 sections that pop up...after just a few fine-tuned adjustments, it's ready to go.
I was at Lowe's the other day and it looked like they had a few really nice trees. You'll find gorgeous ones anywhere so it's best to just go out and start looking!

Some trees will look more full than others...keep that in mind...you want a nice, full tree with lots of tips. Also before you go out and look at trees, measure the space in your house -- not just the height (allow for a tree topper!), but also the diameter. Trees are all different diameters and some will fit better than others in your designated spot.