which of these 80s groups are most underrated

Most of those were rated at or over what they should have been..Maybe Adam and the Ants / Adam Ant were slightly underrated..

The Police 

I wouldn't call any of them underrated in the slightest. With the exception of Pet Shop Boys and maybe Adam and The Ants (my vote) they're all annoyingly ubiquitous.

Chicago IS a 60s group.

Good call.  Was actually listening to Soul Mining on the way to work this morning.

First, several of those bands (Chicago, Van Halen, Journey) are more properly 60s/70s artists that continued into the 80s. Second, when discussing under/overrated, it's always a question of: "under/overrated by whom?" Several of those bands were either highly rated by critics or audiences, but not both.

Of those bands, I'm tempted to say Bon Jovi simply because they were loathed by critics, but I always thought them really good, solid, pop songwriters. They were also one of the best live acts of their era, and Richie Sambora one of the most underrated guitarists. I'm one of the few that actually came to prefer their post-80s work when their popularity declined, especially Keep the Faith, These Days, and Crush. I don't think a single song from These Days made the radio, perhaps because people didn't buy the "Bon Jovi gone alternative rock" style, but I loved it:

I would have added the Go-Go's. Reputation as a schmaltzy pop group. bordering on bubble gum. But they were talented musicians.

Yeah, I went through a "phase," I guess, in my early 20s where I hated pop and most mainstream music, but eventually came back to it several years ago. Bon Jovi were one of the first bands that got me into rock music, so I always had a soft spot for them. SWW and NJ are both really fun albums, but I'd definitely recommend Keep the Faith and These Days as well. I think Keep the Faith is the best "balance" they found between their 80s arena rock sound and the more "serious side" they explored on These Days.