What a CLICKBAIT question....!
And it worked, too.

Just like on all the other people on this thread....
So, let's narrow it down one criteria at a time:
I think, what this thread is really asking is:
What is the all-round do-it-all gun?
Caliber
The .177cal is limiting me to
smaller game, so I'd have to move up to at least a .22cal.
The ammo choices for .22cal are huge, and economical, certainly better than for .25cal. But the .22cal JSB 25.39gr with its
inconsistency is overshadowed by the .25cal JSB 33.95gr, while maitaining a high BC.
And .25cal allows me to go for
medium game (and if I really pushed to some extreme power and used slugs, I might be able to go for
larger).
Whereas in
.30cal, the ammo choices are shockingly small. And for shots where I could damage stuff behind the target, that's really to large. Also shot count is very limited, and prices go up real high when moving from .25 to .30. The shot noise also goes up, so this puts limits on backyard shooting.
⮕ .25cal it is
Gun adjustability
I would want a gun that I can easily adjust power without taking it apart.
That way, I can adjust from barn shooting, to squirrels in the woods, to pigeons on the grain elevator at 80y, to XLR (extreme long range) shots at 200y.
There are few brands that offer external adjustment of both hammer spring AND regulator.
Since I hear so many complaints of
FX barrels getting bumped and loosing POI —
I go against the current and —
⮕ I opt for RTI
Their guns are rock solid, like the RTI owner Rock.
AirMaks would be another option, but I can't stand the silly- and flimsy-looking adjustable buttstock of AirMaks.
Also, to be a true do-it-all gun, it should offer changing barrels and changing caliber. These three brands offer that.
Also, I like guns that are tough and don't look like I have inherited them from my grandfather —
so wood and blueing is out. These three brands fit well.
Gun Type
Not a pistol, not even with a buttstock.
Because I want to be able to shoot from vehicles, pack it for airline travel, and generally hate to increase bulk without gaining function.
⮕ A bullpup it is
Why have a gun with the same power, but a whole foot longer than necessary....?!?
Model
Though the RTI Mora is the newest RTI model, and extremely powerful, while extremely quiet,
⮕ I go for the RTI Prophet P3
(Due to its lighter weight, as a do-it-all gun must be fit for a walking hunt).
Scope
The magnification ranges of 6-24x, 4-16x, and 3-12x are the most common magnification ranges — but they are
not do-it-all....
The most common do-it-all magnification ranges are at least 6-fold and would be
3-18x and
4-24x.
If I have a lot of long range shooting, or if my eyes have a production date more than 40 years ago, I'd go with 4-24x.
But the 3-18x is better for the closer shots (squirrels, ratting).
3-18x in the $400 to $700 bracket are plentiful.
4-24x are much less common, Vector has a good option if you can get it on sale.
I have played through these options for years, looking at pro's and con's of each of these decisions....
Matthias