Take the time to doa little research into what you want.
There are two types of Mini Hums that are popularly available, after market.
1) Is the type that usually sits within a P90 cover/mounting ring like in the photo in the post above, and the pickup has polepieces.These first showed up on the Gibson Les Paul Deluxe in 1969, though a similar looking pickup was on older Epiphone guitars prior to Gibson taking Epiphone over in 1958 or so.
2) The Firebird mini humbucker , which is usually a non polepiece pickup with a chrome or gold cover, and a specialised sized mounting ring to match. These first appeared on the Gibson Firebird in the early 60s....
Both are humbucking, both sit somewhere tonally between the P90/Strat single coil and a humbucker (PAF style). The Deluxe versions are usually hotter in DC resistance, but that throws them more into humbucker territory, while the Firebirds are quite a weaker humbucking pickup and do get quite single coil in sound. DC resistance is not the be all and end all of how hot a poickup may be, and I think the Firebirds might have had Alnico magnets while the Deluxes housed Ceramics....
My suggestion for you would be to look at what guitars pleased you the most over the years and what pickups they had. If the answer is a single coil type pickup, then it may be better to head in the direction of a Firebird pickup, but if you have a leaning towards Gibson LPs and so on, then maybe the slightly hotter version of the Deluxes are more for you.
Of course, nowadays, the after market pickups can be a lot hotter than the production models, so there may be hotter Firebird pickups around and less potent Deluxes.......the choice is yours I guess.
Because they are smaller in housing than the usual humbucker it is natural that you cannot get as many coil winds on the pickup and that will affect how these sound inherently.
From my own experience I can say though, that a Firebird pickup - a good one - is a mighty angry little ant when put to a cranked amp. Ask Neil Young if you don't believe me!
They are interesting pickups but because they are 'left of centre', routings for them are sporadic, even throughout the Warmoth body range (You cannot get a pickguard for a Jazzmaster made for mini hums, by Warmoth, for example. Don't ask me why I have asked twice within 5 years and the answer is still NO.... :dontknow: ). I also don't believe they would sound too great when split, or the humbucker wiring coupled up in parallel. In fact, I'm pretty sure they'd sound anaemic.