What PA does your band use?

Unfortunately reading the “specs” these days isn’t very valuable as they tend to come from the marketing department and not from engineering.

Looking at “Watts” on tells you how much power is being burnt up. It does not tell you how much sound is being created.

The max output SPL will tell you how loud a speaker will get, but it ignores the quality of that output so how much of it is at a distortion level to be usable is unknown. There is no standard for that.

Placing your sub in a corner will easily triple its output at low frequencies with no extra power.

TMI -moving air to describe sound is metaphorical as sound doesn’t travel on moving air ;)

My best suggestion is go listen to a band that has close to your requirements and see what they are using. Then adjust from there.
Generally... We use the venue's PA

I don't know if this is regional, but venues with no house PA tend to be pretty lousy places to play anyway. And I'm too old to be loading subs in the car at 2AM.

If we must bring a PA, we rent one. Typically a pair of JBL PRX 12" tops and one or two (depending on venue size) 18" sub.

Don't bother with 15" tops, the low end should come from the subs, they are just heavier and bigger and yet don't carry vocals as well.

And go for quality over quantity. "1000W" is just a marketing term nowadays, and plastic boxes will never work as good as wood cabinets (they sure are lighter though)
I have a PA system that a couple of my bands use when we need one, but usually venues provide sound systems. One of my other bands has a PA that the “band” owns, for small gigs, but for bigger gigs they hire my PA (basically, pay me to bring mine).

If the room is really bright, I have a powered mixer with passive 2-way 15/horn speakers, with boxes of thin plywood construction which warms up the sound. I also have several JBL EON2 15 speakers, which are powered, powerful, clear, and have very low noise, which work great for projection and coverage. Larger venues and outside concerts really benefit from 4 of the JBL 15” mains, and subs are never needed nor missed.
If the venue doesn't provide sound, our sound guy uses a Behringer X32 digital mixer and I believe EV mains and subs.