Solid wood flooring has an elegant look that you will not get with engineered hardwood or vinyl plank flooring. Some get close but none quite get there. Part of the reason is the fact that with solid wood floors, we usually install them unfinished, and then work with you to come up with a custom stain color. Also, with site finished solid hardwood flooring, there are no beveled edges like there are with engineered wood flooring and vinyl plank. The bevels are there because those types of flooring do not get sanded on site and it keeps you from feeling the edges of the boards.
Another positive with solid site finished flooring is that it doesn't typically get discontinued like the factory finished options do. So, if part of your floor gets damaged, we can get flooring to repair it. Since pre-finished flooring gets discontinued pretty often, you have to replace the whole room or entire floor if it gets damaged.
There are downsides as well. Solid hardwood flooring has to sit in your home for 2 weeks to several weeks before it can be installed and finished. This is so that it can take on moisture until it has the same moisture content that it will maintain over it's lifetime. For example, solid wood floors will end up at around 9-11% moisture content, and new flooring comes kiln dried at around 5-6%. If it is installed and finished prematurely it will still reach 9-11%, but there won't be room between the boards for it to swell, so it will cup/buckle.
Another downside is that the finish that we apply isn't quite as durable and the aluminum oxide finished that are put on at factories over seas. We use commercial grade water based finishes from Bona, and Rubio Monocoat. Both are plenty durable with normal use, but they will scratch from heavy dogs nails, sliding heavy furniture around, and things like that.
That being said, not all pre-finished flooring has durable finish, no matter what it says on the box. Hold a board where you can see it in the light and see how hard it is to scratch it with your thumbnail. If it doesn't take pretty extreme pressure, keep looking.
Some popular solid wood flooring species are: Hickory, Pecan, Oak, Mesquite, Walnut, and Cherry. Hickory, Pecan, and Oak are fairly similar and can be stained pretty much any color. Mesquite is pricey but is very water resistant and is a beautiful reddish amber color. Walnut and Cherry are beautiful but aren't super hard so they dent easily, still great options if you are going for a look that only they can provide. White Oak is probably the most common because of it's hardness, stainability, and availability.
Site finished solid hardwood flooring can be installed in many different patterns if you want to fancy things up a bit as well!