In most cases, it is easy to build a modular system that will cover 80% of your events. The remaining 20% can be supplemented by renting either in part or a whole system.
Consider a modular system for small(er) events:
2 or 4 tops with a 10" or 12" driver
2 or 4 subs with 15" woofers
That will cover the 25 kid case (two tops), wedding ceremony music (two tops), and the 200 person wedding reception (two tops, two subs), and the bar gig with some EDM (four tops, four subs).
You can get a digital PA manager and save the settings for each setup and recall them with the push of a button. That will simplify your setup time and sound check - when compared to using a “new to you” PA system for every event (which is likely a bit extreme…as I imagine that you rent similar gear from event to event).
If the rent -v- buy decision makes sense depends largely on the details of your business, available storage space, how you move your gear to/from gigs, etc, etc. If you have determined that renting is better for your business, so be it.
Given PA cabinets at similar price points, and a double blind test, run at sensible levels (on “5” and not on “11”)…it would be REALLY hard for the average person to pick out a JBL from a QSC. Add in even modest processing from a digital PA manager, and all bets are off - I doubt their gear designers could tell the difference.
40 years ago, cabinets were designed to be reasonably flat in their response - often at the expense of significant SPL. This was done because the digital signal processing we take for granted today did not exist at any price point. Today, for $300 you can get a digital PA manager with capability that was available in 1985 for $50,000 in 40 rack spaces!!! In practical terms, ALL modern PA systems benefit from EQ, limiters, and crossovers.
That said, one system run at “11” and another run at “5” providing similar SPL in the room…those differences are obvious to all but the most tone def of listeners (which does happen). That is more of an issue with having enough “rig for the gig” as opposed to the quality of any individual components. I rarely run my system past about “7” in order to preserve headroom. If I need more SPL, I double the number of cabinets that I bring.
The issues of total cost of ownership, durability, reliability, value for money, etc tend to drive my decisions about gear. But I am fortunate to be able to purchase gear in the mid-price to high-price points where there are many reasonable choices. At the entry level price points there are a few “OK” choices, but nothing that really stands out.
You do not have to go to Function 1 to get quality PA gear…but if you have the $$,$$$, they do make nice stuff.
QCS, JBL, Mackie, Peavey, Yamaha, EV are all making reasonable gear at their middle and high price points. Even Behringer and American Audio have some mid-price point gear that is good value for money (there is always better gear for more money).
Pyle Pro, Gemini, Alto, Kustom (I’m thinking back to my last trip to Guitar Center) are all focused on the “pro-sumer” and “entry level” price points. There overall value for money offering remains suspect to me.