I've been training a good 27 years, and I can probably count on one hand the number of times I've done pec deck flies - and this was many years ago when I was just starting out and trying to figure things out. I tried them a few times and concluded that I wasn't really working my chest to any real degree and was just wasting time and energy. Ditto for cable crossovers and even db flies. And chest is one of my stronger bodyparts that I've always gotten compliments on.
I've always done lots of barbell flat and incline presses, incline db presses, and dips. Occasionally doing a little "decline" work by slightly elevating the bottom end of the bench off the floor a few inches just for a little variety - I'm not into doing decline on such a steep angle that I'm practically upside down.
Maybe a couple of sets of higher rep, moderate weight seated machine flat or incline presses to finish the workout. But mostly just moderate to heavy free weights for a good 12-15 work sets, aligning the body properly and using good form.