I loved the Vita. For the first year after launch I literally used it every day. For the second year, almost every day. It wasn't until the 3rd year that it started spending more time on the shelf than in my hand, as games I was interested in started to dry out, I still couldn't justify the cost of a larger memory card that I desperately needed, etc. I will keep my launch Vita till the day I die (or the battery explodes inside it) and will defend that glorious little thing to the end.
The Switch is better. The experience isn't the same at all. Yes, the Vita got last gen, and some then-current gen ports, but they were a lot more gimped than what happens on the Switch. If not graphically, then at least in the controls department. There were also more limits on what kinds of games could be ported. Borderlands 2? Sure, but it has that cell-shaded art style that made it more viable. You would never see anything like Doom being brought over. Killzone was somewhat impressive, but still a bigger rift between that and console counterparts than what you get with the Switch.
More importantly is the shear flexibility the Switch offers. Not just in the docked vs handheld, but in controller types and layouts, the local portable multiplyer, motion controls vs touch screen. Devs can build games however they want, sure, but what really matters is player choice. No matter where you are or going, the Switch adapts to your needs to keep you playing (so long as there's a power outlet nearby). It keeps the player engaged, knowing that no matter where they go, they can find a way to use it that doesn't feel overly gimped, if at all. So people will take it with, despite it being a bit large, and continue buying more games for it they otherwise wouldn't have. That level of constant engagement is the real game-changer over not only other consoles, but other handhelds as well.
The Vita didn't have that. Nor does the 3DS, or the Game Boy, or any other previous handheld, successful or not. And neither has any previous console. There are very real arguments for not wanting one, especially if you have zero interest in portable gaming (or zero interest in stationary consoles), but even of you are one of those people, I would still urge you to try one. Maybe it isn't your thing, cool, but it very well may change your mind.