Some good comments here, diamonds in the rough as there is lots of BS too, some of it in the "deranged" category.
One of big bore rounds that I found to be surprisingly enjoyable to shoot was .375 H&H in a Ruger #1. I also enjoyed shooting .338 Winchester mag from a Winchester model 70 Sporter Magnum.
I have to admit though that I also enjoyed shooting a .58 caliber H&R Topper black powder gun, even though that was really too heavy a bullet for too light a gun, especially with the heavy loads of black powder we were using. What kept us at was that the topper was surprisingly accurate, and it was fun to watch the reaction when we let somebody who was curious about it take a turn. One time a combination of flinch and recoil actually unseated a shooter, he fell backward off of the bench but to his credit, he hung onto the gun.
One cartridge that interests me is the .450 Marlin, which should be useful here in the US, I'd like to try it out in a good bolt action rifle but to do that, I'd have to roll my own as nobody makes anything like that.
The .458 Winchester mag has about the same capacity as a 45-90, but the combination of smokeless powder in a modern firearm makes it much more powerful than the old black powder round. The factory loads are not optimal for hunting in the US, but by handloading this round, it can serve well for anything from white-tail deer to moose and grizzlies.
In general, the experience of owning and shooting any big-bore cartridge is greatly enhanced by handloading. It gives un-matched versatility and by keeping the costs down allows you to shoot more often.
I have owned several Marlin 1895's, in fact my first rifle, bought when I turned 18 was an 1895g with the straight grip, squared finger lever and plastic butt-plate. That 45-70 carbine taught me how to shoot without flinching. The best 1895 I owned, by far was the 1895CB - the 'cowboy' model with the 26" tapered octagon barrel. It has a great trigger and is remarkably accurate. The balance and general shooting qualities of the 1895CB is as close to perfect as I have ever encountered.
I have to say though, that MOST fun I have ever had with a big-bore rifle was the Ruger #1 in .375 H&H.
- But that's just me.