I hate to bring back the concept of SW1 and SW2 from
@travlerajm but that is essentially what we have going on here.
SW1 would be the range of light swingweights from 300s-320s.
Contains:
Holger Rune - 315
Liam Broady - 315
Yoshihito Nishioka - 315
Adrian Mannarino - 325
Nick Kyrgios - 325
Marton Fucsovics - 325
JJ Wolf - 325
Cameron Norrie - 325
Main characteristics from this group of swingweights being that you have to swing faster on the average shot but are awarded extra touch and feel in return for a lighter swinging frame. These swingweights work best for doubles players or those who need the ability to quickly transition from defense to offense.
SW2 would be the modern pro swingweight range, or medium-heavy range from 330s-350s. Many of today's top pros are in this range.
Contains:
John Millman - 335
Miomir Kecmanovic - 335
Frances Tiafoe - 335
Denis Kudla - 335
Karen Khachanov - 340
Roger Federer - 345
Dominic Thiem - 345
Stefanos Tsitipas - 345
Jack Sock - 350
Matteo Berrettini - 355
Juan Martin Del-Potro - 355
With this modern swingweight range, you lose a little bit of acceleration, but gain predictability and don't have to swing as hard on the average ball. It is still possible to transition to offense fairly quickly with these frames. These swingweights combine the best aspects of the maneuverability of the lower swingweights along with the stability of the higher swingweights, and are a reasonable tradeoff for most pros.
Finally, at the top of the modern scale we have the
SW3 range, or swingweights from 360s-390s. These swingweights pack a big punch and help hit through the court rather than with angles. A game based on depth (i.e. a clay courter, huge grinder) or on big serves may work best in this range.
Contains:
Zverev - 360
Wawrinka - 360
Djokovic - 360
Nadal - 370
Andujar - 380
The reason I have broken the levels in this way is because a racquet with 30 swingweight points higher actually handles similarly to a racquet with 30 swingweight points below. That is, a racquet with a swingweight of 315 will actually swing somewhat similar to a racquet in the 340s, barring the fact that the racquet in the 340s will be heavier and more difficult to handle.
I've tested this premise using a Gosen swingweight machine and a lot of time on court.
Finally, it's important to remember that a big part of what the best players end up using has to do with the racquet they used growing up, as the swingweights they are comfortable with will react in a predictable manner under critical situations. Don't base your choices based on what the pros use! Do what's most comfortable for you.