Older JBL and Electro Voice speakers fit that category. Many times it is more about the cab than the speaker though. People generally put smaller speakers in smaller cabs and small cabs limit the bass feel of size. I have a Celestion G10S-50 in a large, detuned cab and it sounds almost as big as a 2 X 12" cab but definitely bigger and bassier than most 1 X 12" cabs.
There is not really that much of an inherent difference between 10" and 12" speakers. There are certainly some 10" speakers that have more bass and loudness than the average 12" speaker. Whether you are talking about 10", 12" or 15" speakers, they are all fully capable or producing all the guitar frequencies. If you chose good speakers and cabs I am sure that most by far could tell which size speaker you were using. I have a single detuned 10" cab that is very loud and has amazing bass. I made another detuned cab that had a JBL D130 speaker and it had clear and bright highs.
Interesting....part of why I ask is because I use octave pedals a fair amount and need something that can really handle some low notes. I'm putting together a super small/portable rig for a tour and need everything I can get from it in terms of tone, volume, etc....I'm sure there are tons of threads on it, but how do the various Eminence speakers compare to each other? They have very little in terms of description on their website...
I think it is impossible to have, "a super small/portable rig", "that can really handle some low notes". Of course that depends on just how small and low you are talking about. Again, how a speker/cab combination handles low notes is more a function of the cab than the speaker. To get the best, meaning flattest response of the lowest frequencies, you need a large and well designed cab. You can take a fairly ordinary speaker and produce some good low bass in that type of cab and you can get the best speaker on the planet, put it in a small cab and have very poor and limited bass. Long story short, in my experience the best bass you can get out of a 10" speaker is from a single detuned 10" speaker cab. It measures 24" tall X 16" wide X 16" deep. I made one and felt it was too bassy and cut down the depth dimension to 14" and it still has more bass than I need. If that is too big, you might be able to find a Thiele design cab for a 10" speaker. It won't have the bass of a detuned cab but it would be impressive for a single 10" "super small/portable rig".
I've heard from a reliable source that a ToneQuest review of the Jensen Neo speakers found that there was less difference than usual between the 10" and 12" versions of the Neo. I've tried both and would agree that they sound very similar, delivering the tone of the amp with little coloration in both cases.