Hi Katherine and welcome to the forum:
I would recommend checking out You Tube videos from a very respected wedding and event photographer Vanessa Joy, who is very much in the business you are engaging with.
She obviously has a very high budget and likely gets a break from Canon, considering she is a representative for the company. That said, the types of lenses she uses in terms of primes, and zooms, and the focal lengths involved will be helpful, as will the features she values in a camera body. She is actually very approachable, and I would recommend approaching her directly for advice from an expert in the field.
Budget is a pretty fundamental aspect of running a business and I strongly recommend setting yourself a value that you can afford and stick to that. If you arrive at such a number that will impact upon your choices. It might be tempting to go for broke and buy all the latest gear, but unless your business is mature and you have already got a strong series of bookings that will support the outlay, there is financial risk in over-committing. We can make suggestions for the ultimate camera solution that you have no ability to afford, so a guide price would be helpful - also remembering you will likely spend more on lenses than the body.
As regards output. The necessary investment in gear goes up dramatically the larger the output images you produce as a professional. So you need to consider the quality and size of images you will produce.
The Importance of lenses:
Arguably the greatest investment is going to be in the glass. Lenses have a greater impact on image quality than the camera does, and the investment you make in them will last a lot longer - bodies, being highly electronic, change frequently as new tech comes along, lenses not so much.
You have not indicated what lenses you have currently invested in, and that information is critical. As my colleague Demetrius noted, there are issues if you are moving from a crop sensor system to a Full Frame one if you are using EF-S lenses. They would not work at all on DSLR bodies, but can be adapted (with the limitations Demetrius notes) onto the new R-series bodies. If you have EF-S lenses you would be wise to not consider them as viable to use on an R-series body if that is the way you want to go. There are still great cameras in the DSLR range and many are coming on the market as people migrate to the new R platform, so there are bargains to be had. Remember that if a camera took great photos before, it is still capable of doing so in the right hands.
So, let's start with what features you need to support the kind of photography you do. I state these to make sure you see my assumptions and if they are incorrect you can tell me.
Lenses that are fast for use in available light, shallow DoF, suitable for portraits - possibly primes or zooms in the range 50-150mm: e.g. 50, 85, 135 range.
A lens that is good for groups, so something in the 24-35mm range.
Some kinds of lenses that can quickly switch between individual shots of heads and shoulders, through individual -figures to groups - that would suggest a zoom of high quality. Say 70-200 range.
Do you have an investment in any of these lens types? If so, precisely what lens models are they?
cheers, TREVOR
"The Amount of Misery expands to fill the space available"
"All the variety, all the charm, all the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
