I've only been reloading for a few years and consider myself still new to doing this. What helped me decide was researching everything I could find on the caliber(s) I was loading. I started with the load data on the various powder and bullet manufacturers. I would look for powders that they showed as "Most Accurate". Some do, some don't. I also came to the conclusion that the load data in the powder makers info was always a little hotter that other load data information. (My guess was they want to sell more powder!) Nosler is always a go to site for their data because they always show most accurate powders. Buller manufacturers I find more useful than powder manufacturers. Barnes and Nosler have good data. There are also many articles by gun enthusiasts and what they use. I never looked for a powder because it was a "compressed" load or "empty" load. I acknowledge that can and does affect performance, but I guess I too lazy and cheap to test all the powder/primer/brass/bullet combinations available. Search out Handloads.com, Alliant Powders, Nosler, Hodgdon, Barnes, AccurateShooter, Alliant powder is nice because they tend to match powder to a specific bullet.
As far as choosing according to velocity, I would not do that. Instead, I believe it is of utmost importance to learn how to shoot what is called a "ladder". There are several ways of doing this, but this process of loading a variety of amounts of powder shows you which load your rifle likes This is done of course after you have chosen a powder and bullet. Choosing the bullet is as in depth as a powder.
Understand what I have experienced, there is no RIGHT powder. You really have to do your homework and research and settle on a couple (3?) powders and start testing them with a bullet(s) you like and load up and go to the range and shoot the ladder. The whole reloading process is daunting at best. No two shooters have the same answer, no 2 shooters use the same thing. There are trends, but no hard and fast answer to your questions. Not in my experience. Quality components are important too. Good brass, bullet, primers, etc make all the difference. This is a lot longer than I started out to do . . . but the one most important aspect to reloading, regardless of components, is to take your time and pay special attention to being accurate and consistant. Do something wrong and your gun can blow up in your face. My worst "accident": I had been loading handgun loads and I forgot to empty the powder measurer of handgun powder (HOT!) and some of it went into my first few .308 cartriges. I didn't blow anything up (Thank you Savage Arms!!), but everybody at the range heard something wrong when one went off. So, be accurate and careful in every aspect of your reloads. It is really a science more than a sport.
I might also add that I started reloading to improve accuracy in my guns. It to me is the most important reason to do it. I soon learned that using quality components costs about the same as premium ammo off the shelf. (not exactly a "Quick Reply)