I'm watching past Season 2 for the first time since they aired originally.

The change is quite palpable, the production aesthetics definitely went up, but the characters kinda stopped seeming as 'real' as 1-2, a little more caricature-esque, leaning more into their idiosyncrasies for laughs rather than sharp observational wit.

And I still can't stand Ross in any way.
Ross wiggling his eyebrows in the fountain in the opening credits used to annoy the fuck out of me. But I grew to like him.
I loved the show all 10 seasons but Joey and Monica definitely became caricatures of themselves. Thats not Matt and Courteney's fault, but they both become pretty one note. Phoebe gets meaner and meaner, particularly to Chandler, as the series gets towards the end and I never understood that. Why would Chandler ever be friends with this woman? She's an asshole.
Season 1 is a bit uneven, Season 2 is when they hit their stride until around Season 5. Those seasons had a good mix of “real” and ridiculous comedy. They most importantly seemed to be great friends, rather than toxic family members as what it seemed more in the later seasons.
The One With The Lottery is definately a standout of the later seasons. Everything was just perfect. I remember reading on here that they had a contractual obligation to film one episode entirely within the aparments each season. The One Where No One's Ready is easily my all-time favourite. The gay gasp 7 year old me let out when Rachel came out in that green dress towards the end of the episode!!!
I’ve been rewatching Season 1 and it’s actually stellar. Some truly A grade eps here like

TOW The Blackout
TOW The East German laundry detergent

I enjoyed a Friends that didn’t have a Ross and Rachel relationship stigma attached. Was refreshing. Ross obsessing over Rachel throughout did get kind of annoying though.

I wish we’d seen them as Friends longer before a relationship.
No. That trend came a little after it’s time.

Bottle cap episodes are cheaper to produce cuz they only take place on one set. So to cut costs they tried to have at least one once a season.
But not as cheap as a clip show episode I reckon.

I hate those clip show episodes, they are truly lazy and cheap.

Don't know if it's the same in the US, but bottle cap episodes in the UK are usually when the writer is so behind on their writing that production can't plan ahead and consequently they can't do any location shooting, there are usually no extras and minimal secondary characters, and everything is done on set with core characters.

The episode where Miranda has a therapy session is a good example, as is the Staff Meeting episode in Steven Moffart's Chalk.