I replaced my batteries a few months ago as they were also original, I went with Diehard platinum's, which are just relabeled Odysseys. They aren't cheap but IMHO they are the best. Also even though I replaced my batteries as preventative maintenance, I was surprised how much quicker my truck turns over (and therefor how fast it starts), even though my old batteries tested fine, after considering their age, and since I had the means to replace them and I couldn't be happier with my choice.
Yet with all that being said I have an over-sized Interstate battery in my 01 ram 2500 V10 and next month it will be 8yrs old. (yes 8 years old) I don't remember what group it is but it was the biggest we could fit under the hood, although I added water and cleaned the battery a couple years ago. Other than that one battery I haven't had real good luck with Interstate batteries.
So just use your best judgement and good luck.