A warm welcome. I have had a similar experience to you. The Circuit is the ultimate gateway drug to hardware in that it’s a cost effective way to learn what you like. I too found that exporting stuff was a total pain to the point that I wouldn’t do it, and I moved it on.
I think there are 2 things you have to weigh up in your quest - one is portability and the other is fun factor. I’m not 100% sure that you can get both as a 10/10 in one box (except maybe one specific box). But generally as they get bigger they get more jammable - but also less portable, and often with much deeper software. And the portable boxes can be simpler and faster, but due to their size, a bit fiddly. So it’s a compromise. (Some of what I’m saying is from researching and dismissing gear rather than owning it, but hopefully you can use my research to help your own.)
In my case I chose 2 options. Honestly, in a parallel universe I could have picked up the MPC One+ and just plugged that in on the go, but I was concerned about moving it around with the mini headphone jack in the front. I have the Polyend Tracker Mini (which has the same jack as this too, but you hold it like a Kindle, so it’s less of an issue.) I have this purely for total portability. I can take it anywhere and make the core of a song no issues. The workflow is weird in a good way, but it is very much a nice to have on top of my core rig. I also have a Maschine incoming because it’s knock down cheap at the moment, (I wouldn’t pay full price for it since it’s an old device and you never know if NI will continue to support it.) This is to give me a more tactile and hands on workflow to create basic track stems before I head on to work on them in detail in Ableton. Again, this is not strictly needed, but I got a bit of a deal so I thought I’d take the punt.
Like you, I have a desire to make what’s known as downtempo and chill house music, which can 100% be done on a Tracker, but it really benefits from a tactile. What I like the most about the any groovebox is the ability to just bounce stems and import them dry and then process in Ableton directly for more layering and mixing.
Since you refer to the fun factor then the obvious candidates that spring to mind are (in order of price from low to high), Maschine, MPC One+, Digitakt/tone Polyend Play/+, Push 3 and possibly the Deluge. All of these have some similarities to the Circuit whether it be a pad based layout, a pad based sequencer; or just more studio appropriate features than the Circuit which meets your need of easy export of tracks. The trade-offs between them will liekly be around playability and portability.
If you take one of the Polyend or Elektron devices, it feels like the emphasis here is on the underlying workflow of programming beats around a very flexible step sequencer. With Polyend they have a big emphasis on their generative sequencers, with Elektron it’s the flexibility of the sequencer in combination with the performance tools. Then you’ve got the Maschine and MPC which have similarities and differences of their own. Of course with these two the big selling point is mostly the pads and the hands on nature of them. They started out simple, but have gained added features over the years, and users talk a lot about how they help them get ideas down quickly. These boxes are bigger, and with Maschine you are tethered to a computer. MPC One+ is unique in its own way and is maybe the most obvious one here because it is small enough to be portable, but big enough to have some playability to it. It has some nifty Ableton control so when you’re back in the studio you can use it to move around a session and some other basic controls, which is a nice bonus. Push speaks for itself really. There’s also Launchpad Pro, which basically gives you a pinch of the Circuit workflow but in Ableton. However, that does involve having a mouse & keys at all times, but it would be probably the cheapest option of the lot. Deluge I can’t comment on too much other than to say that most people who have it rave about it and it seems like there’s nothing it can’t do if you can stomach the price.
Not sure if that’s useful, but hopefully there’s a nugget or two in there that helps your research.