Any of the .416s are efficient and effective rounds for what they are. You said you're looking for big-big boom, big recoil, big result. The .416s will do it. They're about like shooting 2 .30-06 rounds with 180 grain bullets off your shoulder at the same time, but without the extra recoil-absorbing weight of the second rifle.
The Rigby is the original version of the current crop of .416s. It's in a massive case, so has relatively low chamber pressures compared to the newer ones at the same velocities. That gives easier and a bit more reliable extraction with weak or old brass. None of the new rifles will have issues with that, but 100 years ago it was a benefit.
The .416s are neat because they put out a LOT of bullet-400 grains, usually-at a high enough velocity to be effective out to 275 to 300 yards. They are big enough to do the job against anything up very close, but small enough to still carry velocity to reach out and touch something. Put another way, the round can capitalize on having optical equipment on the rifle. The truly big bores don't have the range to require a scope. (That doesn't mean a scope won't make the shooter more effective, just that the capabilities of the cartridge aren't such that you're missing out on taking shots if you don't have glass on the rifle.
Generally, there's the .416 Rigby, Remington, Weatherby, and the newcomer, a .416 Ruger. They all will kill anything that walks, swims, or flies on this planet very well. I think the Rigby is the most impressive looking of the quartet. It's almost the size of a trailer hitch pin: nearly 5/8" in diameter and 3 3/4 inches long. The Weatherby iteration is about 300fps faster than the others. The remaining three are all more or less interchangeable in real life use.
I've shot them some, and my guide when I went bear hunting in Alaska carried one as backup for me. (I had archery tackle.) I'm a lot more of an archery hunter than a rifle hunter, so I don't own one, but if I were looking heavy, I'd buy the .416 or a .375 H&H. Both shoot very flat, with a marginal edge to the .375, and are heavy enough to do any job you'd want in the hunting realm. My heavy rifle is one of
these:
It's a converted .45/70, that can shoot .45/70 rounds, the re-chambered .457 magnum, or 2 1/2 inch .410 shotgun shells. Specs are a 350 grain bullet at 2200fps, but out of that short little 16 1/2 inch barrel! It packs a good wallop, for sure; it's very light. (Our joke is it kills on one end, and wounds on the other.) It's a pretty handy little package, and something else to consider if you're just looking for big booms and fun when shooting. The lever action is fast and flat, so it carries easily. (I can lash mine onto my pack when bow hunting and there's nothing to gouge me as on a bolt gun.) The niftiest part is the take-down action. It will fit into a briefcase easily. If you're just looking for a toy, it's a cool one!

It's less versatile than a .416 since the range is shorter, but (very minimally) more effective close up, and quicker, while being significantly more compact.
What are you looking at? I'm interested to see what you are checking out.