26 transom hung rudder, 272 sugar scoop and more weight in bilge keels/ less tender and blue interior, 273 same as 272 but white interior.
very good boats and twin keels are very good performance can personally recomend one
I have looked at a 26 & several 27's & sailed a 272.Many of the 26's have outboard engines.The 27 is known to be a faster boat than the 26.The early 27's have a normal genoa with side deck tracks for the blocks,the later ones have the self tacking jib.Tyce is spot on with his analysis IMHO.
We had a 26, bought with an outboard but we later put a Yanmar 10hp inboard into it having acquired a good second-hand one. Smashing boat, sailed brilliantly (despite being a 2-keeler) although a bit frisky in a choppy sea.
Outboard version is tricky to control in tight spaces (marinas) as they don't push water over the rudder.
If you find a good one with self tacking jib and genoa it would be a bonus as the ST jib does lack drive in light airs.
Be very carefull if buying a post 1993 Horizon as some had GRP problems ... Most were repaired, some well, some not so well ... but don't let it put you off as they are very strong boats and sail very well
we have owned 3 hunters - one a delta 25 with the inboard/outboard arrangement (hull shape the forerunner of the horizon 26) and a 272 with both self tacking jib and genoa and yanmar 1 inboard , both good little boats - the 272 we found light and easy to sail and for a twin keeler seemed to sail well - we looked at 10+ 272/3's before buying ours and found huge variation in standard of fit out (as always) and big variation in kit onboard, some very basis often with very cheap kit (instruments and the like) through to others of similar age and price fully kitted - ours (sold 3-4 years ago)had cruising chute and spinnaker and small relative size of the sails meant all were very easy and fun to use- great boat for the fun little harbours round our way such as ryde and bembridge - never regretted buying any of the hunters - we found they "do exactly what it says on the tin!",
if we were choosing again no question we would go for a 272/3 (we think they look much nicer than the 26) and definitely the inboard diesel - as for the selftacker - great in windier weather, underpowered in light winds - handy but not essential and to get the best out of it have a genoa too and be prepared to change sails for the conditions expected or be relaxed about boat not sailing at her best