I prefer stick welding for critical welds. Flux core is similar enough to stick welding and it burns in better than solid wire MIG. Dual shield flux core uses shielding gas and a flux core wire. It produces a superior weld and easy slag removal. It also burns in better and runs hotter than regular MIG. You can get 10 lb spools of it in .035". I buy the larger rolls of .045" because it burns in better than thinner wire and it deposits a lot more weld metal per minute. I only use dual shield for 1/4"+ steel. You can go either way with 1/4" steel. It's not too thick to properly weld with er70s6 solid wire MIG.
So dual shield MIG for critical welds. You also need to crank up the shielding gas to 35-40 cfh. Not a huge issue because you shouldn't be making any super critical welds at your age. Leave that stuff to the professionals. You can practice with it to learn but you need more experience before attempting critical welds.