Four spring to mind.
Early 90s, fully rigid Spesh Stumpjumper (the green one that they re-built as an anniversary piece a few years back). Bought it off a mate and rode it (incl a trip to Chamonix) until it got nicked in 2005.
My first FS bike, 2010 Turner 5.Spot. Regret selling it.
My two current bikes:
2Souls Quarterhorse. Lovely bike, sprightly and chuckable for a hardcore 29er and, slightly surprisingly
2015 Vitus Sommet. Good on the climbs, superb on the downs, loves to get air. Fastest bike I’ve owned. Incredible v4m considering it cost 1600 quid in the sales