I don't think there's one "best" way - there's a purpose for everything and the variety (lolz .. the "Weider Confusion Principle") helps. The body tends to respond best in cycles - if its just changing up completely how you're doing things, going from heavy to active recovery, or deloading phases or whatever. The primary goal I think is to allow CNS recovery. As long as you've got that and you're fueling for your goals, changing up is good.
One comment I will say from my own experience - I've done nearly 30 yrs of 'per muscle group' training, usually 2 muscle groups per day (e.g. back / bis, chest/tris, etc.) which is what I'm used to and what I tend towards, but its also not 'functionally correct' and eventually will tend to aggravate whatever natural push/pull imbalances you have. If you're over 40 you can expect to start seeing shoulder, wrist / elbow, knee / ankle issues, or more core stuff like your hip alignment / tightness of IT band, - and any of these can propagate over time to forcing the secondary muscles to do the heavy lifting that the primaries should be doing.
To that end, I wish to God I would've found a good PL trainer 20 yrs ago and nailed my squat / push / pull. I think at least occasionally mixing in your core stuff / full body lifts as your base will go a long way in the long run. After 40 shit just starts to fall apart and then the whole effort of bodybuilding can become a chore. which sucks moose balls if you really love to lift.