Hey there! There are pros and cons, but personally, I would recommend this: If you don't have space constraints, definitely go for the 5-gallon pots. Outdoors, the difference in yield between a 3-gallon and a 5-gallon pot justifies spending a bit more on soil. Your plants will be happier, bigger, and more resilient.
A little pro tip: Since autos hate being transplanted, plant your seed directly in its final pot (the 5-gallon) once it's germinated. I hope I could help you out! Have a great evening!