Don't discount cast/swaged bullets as well. They can be Affordable and effective, and can be driven just as hard as metal-jacketed bullets (patching), without the obturation issues copper brings (plus, you can be a little undersized and it'll upset fine = less loading problems from fouling). GRT can be your friend when it comes to SML's and coming up with initial estimations for loadings. Goal should always be 98%+ burn on your powder before the bullet leaves the barrel. This minimizes the fouling (means you are running at an optimum pressure for the formulation). Some powders just don't work well with reasonable weight SML's and certain bore sizes/ projectiles.
for target shooting, .30, .32, .338, .358, .375, or .40 are good options
for hunting at realistic ranges, the .45 or even .50 will be plenty (tiny amount of drop difference from the .40 at realistic hunting ranges, but bigger diameter). If you can't get within a quarter-mile of your prey to take your shot... there are other things you need to work on than LR shooting lol.
For multiuse - the .40 or .45 will work fine.
Far as barrels, any reputable MFG will be good. I'm partial to Lothar-Walther (fully custom contours for only a little upcharge), but I am currently using 3 Shilen no5 (.30,.30,.45) and 1 Douglas no5 (.45) 27.75" barrels for a project I'm currently working on (at the time, they were on sale/available at Brownells). I don't know if it means anything but I like the Shilen Barrels better, the material seemed more resistant to breeching operations.