I know this is not going to be popular, but I use Gunk Solder Seal trans seal. I used it decades ago in an Accord and it stopped the case gasket from leaking. That got my attention. For the last few years I use it as a preventative measure for the seal conditioners and so far I have had great results!
IMO automatic transmissions have two basic enemies - heat and slippage. Anything that allows a trans to slip is wiping out the clutch material very quickly. So I try to prevent any internal leaks with the seal conditioner. As for the heat? Trans cooler. I live in an area with moderate temperatures so I try to get the largest one I can fit in front of the radiator.
I LOVE the Magnafine filter and highly recommend it! In fact I have a Ford branded one waiting to be installed on my F150 at the next fluid change. I'd consider them mandatory on the Honda's that don't have main filter in the trans. I recently did a fluid change on a friends Odyssey and installed a cooler and Magnafine. Used Honda fluid with some Solder Seal trans additive. Shift quality was somewhat improved immediately and after a few days was markedly better! He's now loving his 120,000+ mile van. I have seen a few non-serviceable transmissions (Mostly Volvo) and I'd consider a Magnafine mandatory for them too. I mean, who was asleep when they designed that?!
YMMV, but the Gunk/cooler combo is working well in my Camry too. Started using it (When I got worried about it) about 180k and it's continued to shift fine since I bought it at 120k.
Whatever you choose, Good Luck!
