There are so many variables and so many options it's no wonder the subject confuses us all.
We have to remember that the chambering we choose to use just launches the bullet and has nothing to do with meat damage. It's terminal velocity, bullet weight and bullet construction that count. You can put forward an argument for frontal area which would be valid, but in truth the difference is minor between .243 and .308 compared to bullet construction and TV.
Different bullets react in different ways depending on their TV. For example, run a 100gr ProHunter in a 243 at 3150fps and shoot Roe at 50 yds and it will be very explosive, show significant fragmentation and do a lot of damage. Hit the same deer with the same bullet with a TV of 2600 fps and it will behave very differently, fragment less and do far less damage.
From what I have experienced over the years I like to use an Accubond (Long Range in some of the rifles and standard in others). Launch it between 2800fps and 2900fps and it works well from 50yds to 400 yds, probably further. Meat damage is very acceptable and it's very humane, killing quickly, fragmenting in the front 40% and remaining solid in the back 60%. Always exits, always produces a good blood trail.
I have used SST's and Nosler BT's but find that TV has to get down to 2500fps and below before damage is acceptable. They kill very well if you're a LR specialist as does the Amax, but TV has to be low and if you take a shot up close and you will make a mess.
I have used Barnes TTSX and LRX which were excellent if launched much faster, around 3000fps. They flew very straight, expanded well and didn't fragment at all. They killed quickly and efficiently but they always exited at pace and rightly or wrongly I got a bit twitchy about deflection and ricochet in areas that had a lot of footpaths and dog walkers. They did surprisingly little meat damage considering the velocity, never ruptured the diaphragm and I got a very large % of bang flops. If shooting a bit further out (over 300 yds) I wouldn't trust them to expand sufficiently however. I wouldn't take a neck shot with them either as the lack of fragmentation makes the target a bit too small.
Placement too makes a big difference. If you are a head and neck specialist you want a seriously fragmenting bullet. I know a couple of stalkers who just shoot head and neck and kill everything with a 55gr BK in very fast 22's. It works for them, but when they need to take a recovery chest shot at 300 yds they are in trouble. A chest/shoulder shot needs something a little more stout.
Go to NZ or some part os the US where a 600yd plus shot is common and you need bullets that expand reliably at 2000fps. The Amax (replaced by the ELDX/M) and the Berger are king here. They wouldn't touch a monolithic bullet with a barge pole and are pretty scathing about most bonded bullets. It's a very different style of shooting to most of ours.
You have to match the construction of the bullet to it's terminal velocity and the type of shooting YOU do.
In terms of species I think the Scots have got it right. I would much rather shoot Roe with a 60 or 70 grain bullet, it's as much as they need and drops them just as quickly as a 100gr doing less damage. All Fallow and Red and Sika hinds are fine with 100gr but I always go 130gr or 150gr when shooting Red and Sika Stags. If I was shooting lowland red hinds I might move up to 130's too, but I have never experienced that so am not really qualified to comment.
Just my view, others I'm sure are different.