Many good points here. I assume we are talking about field dressing contra to skinning and butchering; which, IMO, are more easily done with different knives than what I prefer for field dressing. Yes, one or two knives can do it all, but will address field dressing.
I've been hunting a long time and have blessed to have harvested and field dressed many, many critters - especially deer. Though shorter and longer will work, I have found 4-5" to my personal sweet spot. As stated a fair amount of belly certainly helps and not too pointy; although, more pointy can work if you've got more curve to the cutting edge ala Old Timer 1650T or the now rare and highly sought after Becker BK15 - both trailing points. On the subject of Beckers, the discontinued BK17 is also a great deer knife as is the (still in production) BK16 - especially if you like carbon steel and the ergonomics of Ethan's handles, which I do on both counts.
Looking back, I have done most of my deer with a Buck 110 mainly because it's what I carried as a young man and simply used the knife I had. I later bought an Buck "Special" Model 119 and though bigger than necessary field dressed a bunch of deer and my first elk with that knife. Neither is my preferred knife for field dressing these days.
I progressed to smaller knives (3-4") and found them quite suitable. They don't poke you, get caught or otherwise get in the way when getting in and out of vehicles and what not. This assumes you carry your field dressing knife on your person instead of in a pack. On that point, though I always have a knife one me, I find a knife in a pack more accessible when the time comes rather than undressing just to get to a belt knife.
I got way too many knives and anymore like 4-5" fixed blades with grippy handles. Though I like the Cold Steel Drop Forged Hunter very much as a woods/camping knife, I was underwhelmed by the deer I dressed out with it. The handle is cold - and slippery when wet, it's too tall edge to spine for the delicate but important task of separating the lower GI from, ah, where it exits the deer. Though not my favorite deer knife, the Old Timer 1650T and the venerable Buck 110 are well suited for that end of the job. It did perform all other aspects, especially opening the chest cavity with aplomb. In fact, a Drop Forged Hunter with paracord coupled with a Buck 110 or Mora could work; but the paracord (IMO) isn't well suited for deer gutting knives and if you have to have a Buck 110 with you anyways - it's a but of a solution looking for problem. Seeing as I mentioned Mora; no, they don't have the charm of a proper deer knife but - they are inexpensive, lightweight, can be had with orange handles. You loan them and lose them without needing therapy and they work!
It should be noted that one time, when I hastily changed clothes from work to hunt one afternoon, I found myself with a deer and no knife - not my fixed blade nor been my pocket folder which was in my suit pants back at the office. I did have a SAK with me (thankfully) and, as expected, that sharp edge and flat grind worked like a charm - except when I was tugging on the esophagus with my left hand and seeking to sever the windpipe and nicked a small chunk of my left thumb. It was cold, I was rushing and WOW that instant transfusion of deer blood into a fresh/open would sure crossed my eyes!
So, I said all of that to say this: my current favorites are the Cold Streel Master Hunter or the Cold Steel Pendleton or Mini Pendleton mainly for the handles, blades sizes, blade shapes, grinds and spine thicknesses; they just seem to work for me. Although, because of a change in packs (from a walking hunt to a sitting hunt) I dressed my last deer with my go-to hunting season pocket folder, (forgive me Mr. Buck), my orange handles Ontario RAT-1 in D2. It worked great though the sternum (or ribs or ??) did leave a couple small chips in the edge.
That's what I've used and currently use but those older Marbles Knives I have in 52100 with leather stacked washer handles and a leather sheath still call to me from a Tupperware tub under the bed ... as does my old Buck 110 when the leaves change and the rut is approaching.