In general, shop for the highest value of Amp-Hours that fits your budget.
This spec typically applies to deep-cycle- or marine (hybrid) batteries. It's really not applicable to automotive starting / lighting / ignition (SLI) batteries.
So, I got an amazing deal on a '99 Forester with less than 69k miles on it. However, it still had the original battery, which died shortly after winter hit us here in Ohio.
Does anyone have any advice for choosing a solid replacement battery?
Considering your location's fairly cold winters, I'd suggest looking for the correct size battery (BCI Group 35 or 36?) with a high CCA spec. CCA = Cold Cranking Amperes, a measure of many amps the battery can supply at 0 degrees F for at least 30 seconds down to a specific voltage. Some manufacturers spec 10.5V (for a 12 V battery), others 7.2 V, which is not quite as good. Cold weather reduces effective battery capacity, so a high CCA number should help.
There are many battery brands, but few major battery manufacturers. Johnson Controls, Exide, and Interstate make many of the various brands available. Look for a fresh battery (<6 months old) by checking the date stamp on the battery.
Consumer Reports tests batteries in accordance with an SAE spec. Moderately-priced Group 35's that tested well included models from Kirkland (Costco), Everstart ("N" model = "North"; Walmart), and DuraLast (AutoZone). The batteries' product labels may identify the actual manufacturer.
My personal experience with Interstate batteries is mixed. The new one in our Honda appears to be working well, as did the one in our old minivan. However, the big 875 CC Interstate "85 Month" battery in our pickup appears to be fading fast, although it's not quite three years old. It's needed several jump-starts and recharges over the past couple of months, and I'm looking for a parasitic load.
Jim / crewzer