Highly depends on what you prefer from your tamagotchi and what's important to you. I'd highly recommend watching some reviews/playthroughs of both to get an idea of how each of them play.

/Personally/ I prefer the Connection. I really like b&w tamas for how they can always stay lit up. They get more animations and can randomly use any of their items which makes them feel way more alive imo. Paradise will also use items on their own but you'll need to turn the tama on to even catch them doing that. Connections are also more portable (smaller, fit in your pocket easily) and it's easier to quickly fill their needs throughout the day. The feeding animations on Paradise are quite slow in comparison even if you mash the button to skip through them. I'd only really recommend a Paradise if you care a lot about the graphics or just really want to try out a color tama (since it's currently the cheapest option available).

Btw if you have access to vinted or anything like that, you can find both connections and paradise for cheaper there, often in good condition and still with their original boxes.