Depends on how your OCD leans, if it is bothered by non matching widths, then a 112 or 210, but the 112 was discontinued . if you subscribe to matched drivers or fear the MDP (mixed driver police), then the 115 makes most sense. It is wider than the combos and 112/210 cabs. Though it is a closer match with the combo on its side, or the cab on its side, or just have a wider bottom cab which is really no big deal.
I had the 112 and now I have the 210 and only because the 112 got stolen and they are not easy to find. My avatar pic shows it with the 112. With the 112 the bottom cabinet is shorter than the top cab but it looks cool and they are the same width. The 112 plays nice with both the 200 and 500 combos, the 210 will push more lows and highs but less mids than the 112.
My rig does seem more powerful than it did with the 112 but this is just from memory, and in the past I lived on a boat and the amp and can lived in the car so I only used them at shows and practice and did not critically examine the difference in sound between the 15 and the 12, it just made the whole rig louder and fuller
When I got the 210, now living indoors again, and also playing guitar at low volumes through it, did I notice the large difference in mid response of the 15 vs the 210. Along with that being a common thing, 15 s and 12 s have more mids than most 10s. You could consider the 12 as the middle ground.
Also for pure air pushing, the 115 will push the most air because 15 is more cone area then 2x10, and the larger cabinet size helps as well. So the 12 pushes the least, and 210 is only slightly less than the 115.
And the 210 is a hundred bucks more than the 115.
Nobody would argue that the 115 will be the loudest and have the most mid punch, but the 210 looks better and being smaller makes a more compact rig, as well as a perfectly matched stack. In an ideal world we would have a 115 offering that also had the same dimensions.
For me it was whichever of the 3 popped up at the best price clpse enough . a 115 popped up as part of a rig that I may have been able to split off for a good price but it was too far away for me to jump on, being a good $30-40 in gas. My 112 was $150 negotiated on here with a meet in the middle drive, but you won't find deals like that often. $150 would be my jump price for 115 as well since both the 112 and 115 are 299 new.
When I saw a 210 pop up used for $169 on GC I jumped because they ate usually over $200 sometimes $300 used. Well after tax and shipping to nearest GC it ended up being almost $230 but I have no regrets, and won't be looking for any other cabs unless I come across a micro head first, like a 200 500 or MB200 etc. In which case OCD takes over and the desire for the ability to have 2 cabs to run with the head will kick in.
As far as the 800, I'm pretty sure the only difference is the power section which is where the 2 ohm capability comes in.
But if you are leaning towards the 200 or 200c the 200c gives a better value, but a 200 on a 115 will give you more bass, or the ability to roll the bass back to reduce mud and thus gain more headroom in your mids. You can get slightly louder with a 115 cab this way, but it costs considerably more, and the 200c has a tighter response.
I did compare at a sam ash, a 200h/115 vs a 200c, and the 115 required the bass knob to be cut because of the boomier sound. At that time I no longer was interested in the 115, but after thinking back on it I realized that it could be used as a source of a bit more volume because of the added headroom gained from cutting the bass knob.
If you like a boomy cab, the 115 will give you that.
Another note, the 210 and 112 are made in the eminence China factory and have a slightly nicer fit and finish than the 115 410 cabs and the combos made in Indonesia, but that also makes them slightly heavier for their size too. My 210 is a little heavier than the 200c but not by much .
200c and 115 is probably the best bang for the buck.
If I still had my 112 that is what I would still be using, and if it was still available new at 299 I would suggest it over the 115 at the same price unless you needed the maximum possible volume, like a downtuned metal band