If I read the OP correctly, you have decided it is a matter of when, not if you endeavor to get your Big 5. I've had my Big 5 since my leopard hunt in 2016. And have taken 3 buffalo and a second lion so far. I have also been in close to many buffalo which never gave me any anxiety.
Elephant;
Elephant had me concerned a couple times. We stalked in close several times on elephant before finding the right bull to take. I know there are some real adrenaline junkies who specifically hunt tuskless cows for the danger level. And the elephants that raised the hair on the back of my neck were cows and young bulls. During the hunt I can say I was at a higher state of awareness several times. But never afraid. After getting home from my elephant hunt, at first I just wanted to get back and do it again! Then after a year or two, and a PH friend getting killed as well as some others who people i know, knew first hand. I was contemplating elephant hunting and came to the conclusion they were indeed very scary and right up at the top for me. I realized I had been in a couple tight spots that we came out of just fine because everyone (well except one tracker) remained calm and followed the PH'S instructions to remain still at times and move quickly at others. They really do know what they are doing

In 2021 while tracking buffalo through some really thick bush along elephant trails high up in Tanzania, we heard elephant breaking branches and i was ready to go after them and have a look! It would have been Legal to take one but unlikely to find a good one. And we were hot on the Buffalo. In any case, I was ready to go after elephant again
I don't know what level you are at financially, but right now is a great time to hunt elephant! My opinion is that the safest elephant hunt is going after lone or small groups of old bulls. And if you do a little homework, you should be able to get your trophies into the US. However you can have the same experience hunting non trophy, non exportable (different than non importable) for about half the money. And of course hunting a tuskless cow is also low cost but likely the most dangerous. I would put hunting bulls in a herd, especially a mixed herd as second most dangerous.
Leopard;
I always joked I was going to wait until I was in my 70's to hunt leopard. 1. Because sitting in a blind is easy. 2. Because if I get scratched I won't have as long to live with the scars

Well I've been in on two leopard hunts and neither was boring. Both required physical exertion, although the dog hunt much more. And neither seemed all that scary. Both were very exciting and I can't wait to repeat!
Hippo;
Lion is probably second on my list of scary dangerous game. Well, third behind hippo on land

I only hunted Hippo briefly when we found good sign in Tanzania. It was in tangled brush with hippo tunnels through it. You would pear around each corner not sure what might be there... That was intense as the spor was very fresh and wet yet.
Lion;
A lion will kill you. But the situations I was in hunting them didn't seem all that dangerous at the time. When you see one peering out of the bush at you, it will make your hair stand up! My first was baited and although the old Africaaner PH was trying to get me nervous and excited, it was from a safe distance and the lion seemed unaware or didn't care we were there. It was a whole big piece of South Africa BS supposed to be "wild lion hunt". After it was over it became abundantly clear I'd been had by professionals.
If you do a lion in South Africa, do it with someone who tells it like it is and enjoy it for what it is. If it sounds to good to be true. It's not true. I learned the hard way. However I had the good fortune of hunting a real wild lion in Tanzania. We actually called it in, roaring like a competitor make. He came in like he owned the place, well because he did i suppose! I will never forget the sight of him stepping out ofvthecbush in all his glory looking as big as one of my Holstein cows, but with teeth and claws. I'll relive that forever in my mind. And I'll do it again if I get the opportunity. Or better still, be there with my wife as she does it!
Croc;
I've seen Crocodile in the wild and spent a few hours hunting one in Mozambique but just as he was swimming around thinking about coming onto the beach, it started raining hard. The PH called it off because of where we were we had crossed a large dry creek and if it filled with water, we would not get the truck back to camp! I really don't think a croc hunt is dangerous for the hunter. Just requires very accurate shooting.
Rhino;
Considering what the situation is, I had a really fantastic white rhino hunt. I had to crawl a good ways through short grass and hiding behind small termite mounds to get close to shoot. Then shot it from a sitting position with my Ruger RSM in 505 Gibbs. The most dangerous part was walking to find him, day 3 or 4, a buffalo bull ran out of the brush up ahead and headed down the trail towards us but veered off before getting dangerously close. Unless you hunt a black rhino, and I believe you can now dart one in SA, I don't think this is a real dangerous hunt. But done right it can be a great experience.
Buffalo!
I think most agree this should be your first DG animal to hunt. You may enjoy it so much you never want to hunt anything else! I could make a case for Leopard being first if you want to also shoot a lot of PG simply because you need bait! The danger level with buffalo has been discussed at length. To me they are the Devil's Red Eyed Cattle. But they are cattle and in general behavior is similar to the cattle I've been around my whole life. I can't even smell them until right on a heavy amount of fresh manure because I'm so adjusted to that odor. However buffalo, cape buffalo, have an attitude like no other cattle. And a tenacity to keep living. And they can be vengeful. But shoot them properly and keep shooting them until you are positive they are dead! No stopping for high fives until the tracker or PH has touched the eye with the sticks