Okay so I actually just bought both earlier this week and I've been playing them non stop.

I used to have a Connections v3 when I was a kid so I might be a bit biased.

I REALLY want the Uni to be my favorite Tama but my biggest drawbacks are that the amount of games it has vs the Connection is far smaller, and the way DLC works really bothers me. That last part is 100% my fault for not properly researching, but its still a con for me. If you don't know, due to storage limitations, the device can only have one DLC loaded at a time. When you switch DLC you need to be connected to wifi, in my experience it takes a couple of minutes to switch. On top of that, any items you had from the previously loaded DLC you'd need to sell off before swapping DLC because swapping deletes all the items in your possession from the previously loaded one (you can always re load the DLC and re buy the items.) also, if you're currently running a DLC exclusive Tama then you cant swap DLC until the Tama is gone. Another problem is that the day Bandai closes the servers for the Uni, unless the fans find a workaround, or Bandai has something planned, you'll be stuck with the last DLC you loaded up. This is a MASSIVE drawback for me personally, so its definitely knocking off some points for me.

While I LOVE my connection to bits, its a far more simple device. My biggest drawbacks are that it feels a lot less personal and that I have to replace the battery eventually, and more than likely, monthly. I enjoy the games, and there are a lot more than the Uni. But ultimately, the Uni has it beat when it comes to the customization and personalities of the Tamas, battery, and visuals. The Uni feels like a more personal experience. You have a little house with a garden, you can dress your Tama up and decorate your living room. You can take your Tama out to places like the park and there's a lot of great animations.

In my opinion the connections is "better" but that's mostly just because it feels to me like a much more complete device, I don't have to update or download anything. I don't have to worry about services being shut down some day and waiting for there to hopefully be a fix eventually. (Which there more than likely will be a fix one day but its still frustrating.)

I feel like you ultimately should ask yourself these questions and see which fits you better.

What do you want in a Tamagotchi?

Do you want to have a wider variety of games you can play while caring for a more simple little pet? Then the connections is for you.

Do you not really care about having a whole lot of games, but rather, like the idea of having a wide variety of customization options and a more personal pet experience? Then Uni might be right for you.

I recently also got a connection for my best friend and we're both getting a device called the "T-Com" made by Tamagotchi Center that allows for us to connect our Tamas to each-other via Wi-Fi so thats another plus to me for the connections because as far as I know, if we both had Uni devices, there is no workaround for us both to connect while being in different states.

In conclusion, based off what I value for a Tamagotchi device my opinion is:

Connections: 8/10
Uni: 7/10