Go to rifle is the tool kit question.

Depends on the circumstances.

But I will attempt it.

In practice and personal history, if I need a medium hunting rifle, my first and original medium calubre rifle is picked up. My customised Parker Hel M98 in .30-06. Have hunted the NT with it for pigs, donkeys and buffalo. No buffalo sighted that trip. Africa on my first safari for plains game. Both of my trophy red stags in NZ and Australia. Fallow deer numerous. Pigs. Many many donkeys. My one and only sambar. Hundreds of feral goats. Hoppers. My old reliable. Capable of one-third MOA accuracy. Easy to get ammo around the world if necessary. Adequate power for all medium game and even capable of dangerous game.

My dangerous game go to, is obviously my .450 No.2 Nitro Express WJ Jeffery double rifle. With the gaur engraved on its boxlocks, it is my specialist bovine rifle. Well pwoerful enough for bovines in thick jess or jungle, and also for elephant. Accurate enough. I do have to do more load development and also test shooting at longer ranges ie 100, 150, 200 metres. To see how it goes. I settled on an early load which worked. And try lighter 350 gr bullets.
Have used it on water buffalo, banteng, scrub bull, horses, donkeys, pigs, deer, elephants, warthog and ?

Next would be my .222 in Mauser M03. Small game at home. Similarly my CZ .22 Magnum bolt action.

My .375 Whitworth M98 for when a "big bore" bolt action is desired. Now works very well.

We can't have self defence rifles here or semi autos like an AR. But my Browning BLR in .308 provides a good rapid fire, very accurate, powerful medium calibre rifle of short length perfect for scrub hunting and rapid fire on game animals. Used on pigs, deer, a chital stag, I do want to use it on sambar. Need some 180 gr Woodleighs first. I don't think any arrived in the latest bacth. The rifle is handy short enough and light enough with sub MOA accuracy to use even as a mountain rifle.

If the zombie/covid strain apocalypse started tomorrow, this rifle, BLR is what I would have on my shoulder. Magazines are too small, five cartridges, and can not be longer as the lever gets in the way, but I have three of them. They were needed on one donkey hunt.

A go to rifle depends on the circumstances.

I do have some others which need to be used more, and more hunting opportunities. Som may become go to rifles of choice.

My fantasy go to hunting rifle around the world would be my desired .375 double rifle with a scope. One day.