One Hot Minute is largely a unique RHCP's album. Dave was obviously a huge influence there. Possibly the darkest Peppers record.
Blood Sugar Sex Magik is great because of the handful of stand out songs it has, namely the singles + I Could Have Lied and the title track. It's a very long album, and it drags a little toward the end, but overall the non stand out tracks are fairly listenable.
The earlier works experiment in the Funk / Rock thing going on in Blood Sugar, minus the mainstream ballad stuff. Freaky Styley is the best of those ones, and it and the first album both have a nostalgic underground feel to it kind of like Gish. I don't think they're very good, but listenable all the same.
However I couldn't get into Mothers Milk or the Mojo whatever. There seems to be a halfed ass attitude on those records, probably from all the drug addiction going on. Blood Sugar was a huge lift in this regard. They actually made an effort to make an album with that, and not just string a few songs together.
Californication and By the Way are very mainstream. They left their funk origins behind and focused on the catchy choruses and the vocals are much cleaner. They lost the gritty feel some of their early work had in favor, but more than make up for it with the quality of songs and overall album feel. You could say they started acting like pros from this point.
It's very hard to separate which is better of these two. Califoniacation might be largely more consistent and has less filler songs than By the Way, and it also has the better singles. But By the Way often surprises with it's hidden treasures, and unique soundscape. Closing tracks Minor Thing and Venice Queen have to be up with the best Peppers songs.
Then they lost it. Stadium Arcadium is a double album that should have been a single. There are some good songs on there, but they are few and far between. Mostly they sound like they're trying to recapture what they had with Californication and it comes off as a weak imitation. The songs are very soft, lyrics cheesy, and everything is just mediocre overall.
I'm With You starts out quite well actually. The first few songs of the album go to new territory, but then the album soon backslides into disposable track after track. Eventually the whole thing feels forgettable, perhaps even more so than Stadium.
Hope it helps