All of my 9's, .40's and .45's are reliable ... or else I wouldn't continue to own them.
The 9's are usually easier to run hard and fast than the similarly sized .40's ... but working to run the .40's hard and fast makes me do even better using my 9's. Chicken or the Egg. Pick for yourself.
My .45's (full-size, medium, compact and subcompact models) are all fine, but they're typically larger and heavier than 9's and .40's that are close to being similar in size/weight.
I was a .45 guy for many years before I grudgingly came to accept 9mm, and it took me about 10 years after the introduction of the .40 before I seriously considered spending my own money on one. Now I own 5 of them, 5x9's ... but 9x.45's. Guess I still have an affinity for .45's.
I've tried to condense calibers before, and it never lasted very long.
If I were to consider trying it again ...
My compact and subcompact 9's are easier to shoot, and convenient to carry.
My full-size, compact and subcompact .40's are convenient to carry, but continue to take more range time to remain skilled in running them hard and fast.
My .45's cover all the range of size/weight ... and I've been shooting .45's for more than 50 years. (For comparison, I've only been using 9's since the end of the 80's, and .40's since about 2000.)
Now, another consideration is the effect of recoil and wear & tear on both the guns and the shooter. It's not unusual to hear longtime Magnum revolver shooters, and longtime .45ACP shooters, discover there may come a point when shoulders, elbows, wrists and hands may require going to the lesser recoiling 9mm. You at that point yet? I'm not, yet, and I'm closer to 70 than 65. Tired & repetitively worn ligaments and connective tissues, and arthritis, may cause a re-evaluation of things like "calibers" in our later years of shooting.