$300 budget
Best speakers is impossible to answer IMHO. I have 13 sets of speakers that I picked up at yard sales, ebay, friends. I have maybe $300 invested total. They are Bose (vintage and newer), BIC, Advent, Sansui, Dahlquist, SpeakerLab. I also have somewhere north of 12 receivers. Marantz, Pioneer, Sansui, Yamaha, Technics. I also have dynamic range expanders, Revebs, graphic equalizers and parametric equalizers. I even have a surround processor. At times I thought some of the speakers were terribe. But swaping things around proved that I could get incredible sound from any of them. Sometimes, just a different receiver, sometimes with an equalizer, sometimes by moving the speakers to a different location. I personally like classic hard rock. I have a basement man-cave with hard floor and surroundings. I moved junk out and put in a rug, things changed. I personally like "quality volume" AKA Loud but most of the time listen to "reasonable" levels. Some speakers take a lot more power to sound nice.
This is one question that has answers like, "it depends" and "your results may vary". My ears are not your ears. I have a freind who flips speakers. He usually refoams them and has a pile of parts so he restores some and frankensteins some. Some things he thinks are great do not impress me but he always plays stuff I am not familiar with so I have no basis for judging. I've gotten some great speakers from him cheap because he thought little of them. I'm sure it was his musical taste and the market price and demand locally.
I think you are on the right track though. I have never heard newer speakers that had any impresive sound for my tastes. But, I may not have heard any good newer speakers.
I know you can make things sound a lot better with a good graphic equalizer. It adjusts the system to the room. A parametric equalizer seems to really make things sing. I just started playing with those.
I would suggest to anyone who is asking this question to please tell us what the music choice is most common, what your are driving the with, what the listening room is like, what you like to hear.
There is a LOT of difference. A wise freind once made a comment as we walked past a music equipment store years ago (70s) as I said "wow, what music is playing, it sounds good". He said "be careful, anything on that system will sound good". They ran all the demo equipemnt through a Marantz 500 hooked to a set of JBL Voice of the Theater speakers. Probably had it tuned to the room with a lot of other stuff (no idea what peramp). I don't know if it was just the best equipment I had ever heard that impressed me or if it was truly good sounding but the insight he shared always stuck with me.