Its very subjective,
It depends on so many things. One's frame history, ability to generate one's own pace, individual sense of feel and depth control, what inspires confidence, etc..
ME, MOST of my contemporaries and MOST of the players I play and coached, who have progressed to higher levels of play, have stuck w/ player's style frames. There are a few exceptions, but the majority has chosen to stick with player's sticks. It isn't vanity, it isn't "I want to play with what a ATP player hits with". And, it isn't that I'm a masochist and wear frame choice like a "hair shirt". Its what I feel most comfortable w/, gives me the most CONFIDENCE to play well, and doesn't cause me to question my equipment choice.
Having started with wood, I learned to generate power and had it drummed into my psyche that it was better to err LONG than into the net. Pace generation is not an issue I "NEED" a frame to help me with. My frame history? Kramer Autograph>Head Master (aluminum)>Wilson Pro Staff 85" (thru its various moniker adjustments)>Prince Precision Response Ti (after layoff and rushed comeback lead to a bout w/ golfer's elbow) and finally, Yonex RDX 500 mid.
TO ME, the Ti was a nice stick and the easiest COMPROMISE for me to heal, for the first time, a dodgy elbow. That frame has been alternately described by others as a player's and tweener frame. It was a nice frame, relatively flexible, w/ mass for stability, but a slightly wider body than frames I have always gravitated to. I played well with the frame, but ALWAYS in the back of my mind was the DOUBT of when that infrequent, unexplainable FLIER would sneak into a point.
FOR ME, one of the "advantages" of wider bodied tweener or other modern frames, added pace, is the very thing that makes me shy away.
"Lighter is better". Again not to me. Much lighter frames inherently FEEL less stable or toy-like to me. IMO racquet weight isn't CAUSING fatigue, reaching one's overall conditioning limits IS. (I know I'd be better served shedding 7 pounds from MY frame, as opposed to an ounce from my racquet's).
Personally, I haven't found a wider bodied frame that affords anything like the feel of more traditional thinner beamed players frames. Not for drop volleys or other TOUCH shots, but for KNOWING on core shots, the difference between driving the ball to various targets and adding/reducing pace or spin. Wider bodies feel vague to me and my target zones have to expand to accomodate MY perception of the lesser accuracy they provide. I define that as FEEL or FEEDBACK.
And, whether psychological or not, the radar gun and results say I serve more effectively with a small headed players frame.
Granted Tweener, Game Improvement and even lighter wide bodied player's frames do allow a player to put something extra on the ball even when pulled out of position or caused an emergency by an opponent's shot. But are those the vast majority of shots one hits? IMHO they shouldn't be. Beyond that, these type frames can ALLOW players to lapse and fall into habits which are less than optimal, because one can and still hit a forceful shot with them, when doing so. THIS, I see as a POTENTIAL problem for the younger developing player who is willing and can put in many more hours of practice than I can now.
Let's face it, one human trait, we all have, is laziness. If we can do anything faster with less effort we will gravitate toward or slip into it almost like water seeks its own level. On its face "faster and less effort", SOUNDS GOOD BUT, such frames, in such hands, CAN promote shortcuts in mechanics, footwork and other fundamentals which COULD ****** one developing a sound tennis foundation. And, IF those flaws are in one's game, they WILL eventually be exposed WHEN competing at higher levels. For others, forced to make concessions to age, loss of more than a couple of steps, injury, continuing difficulty generating pace, or a myriad of other GOOD REASONS including THEIR PERSONAL PREFERENCE, lighter, wide bodied, fringe player's, tweeners and game improvement sticks ARE THE RIGHT CHOICE.
JMHO but aside for ALLOWING players to slip into and/or get by with less than optimal mechanics, there may be other costs involved. With less mass in a frame what is then absorbing impact. With the stiffer, large heads in that category if not centering the ball consistently there is more tourque and jolt going somewhere. NO MATTER WHAT FRAME ONE PLAYS, YOU HAVE TO CENTER THE BALL.
Again, this is only an opinion but I think injuries may start to manifest themselves in recreational players as a result of these frame choices combined with our non-professional level execution of technique. As I'm going to be able to tell my kids that we used to be able to fly the Atlantic above the speed of sound but the costs involved put an end to it, we may see a technological roll back in frame design in the future because of their hidden costs. Again that's JMHO.
Just as with grips, stroke idiosyncracy and practically every element of our sport, SUBJECTIVE PERSONAL PREFERENCE should be the primary factor in frame selection.
Also some posters have implied or stated outright that traditional player's sticks and modern technique are somehow mutually exclusive. This IMHO is patently untrue. Forget the Federer's, Safin's and Hewitt's. Myself (47) and many of my generation, as well as younger players at an advanced level, use "modern technique" and traditional frames. That assertion is just wrong.
Are traditional players frames for everyone? NO. But, to summarily dismiss heavier, headlight, smaller head, thin beamed player's frames as wrong for everyone, is disingenuous.