Advice Best Ticketing Options for Seniors Traveling in Europe?

We're two seniors (78 & 80) planning our next trip to Europe, and we're trying to figure out the best ticketing options for trains and buses. We've heard about OvPay, ChipKaart, and others, but we're not sure which would be the most convenient and cost-effective for us. We've always traveled on our own, no tours except for local ones, so we're looking for something straightforward and easy to use. Does anyone have experience with these ticketing options, especially as seniors? Any advice or recommendations would be greatly appreciated!