I've done the Bealach na Ba from both sides. I'd say doing it from the Loch Carron side is marginally better. Both are absolute belters.
My other top rides would include:-
Hardknott & Wrynose (I needed a 12-32 to get up the former)
Rosedale Chimney in the North York Moors is a 33% monster
Honister Pass in the Lakes - great from both directions
Bealach Feith nan Laogh near Strontian - again good in both directions but from the west side is a killer & is the longest hardest & most sustained climb I've done in the UK
The Lighthouse climb on the southern tip of the Mull of Kintyre if you want a fearsome & remote challenge
Park Rash near Kettlewell in the Yorkshire Dales - so steep I went over the handle bars on the decent!
Great Dun Fell near Penrith - if you only ever do one climb in the UK make it this one......
And one esoteric gem. Calum's Road on the Isle or Rassay - read the story then go ride the ride.
And to finish here are climbs on my hit list.
Shibden Wall & Trooper Lane in Halifax
The Serpentine on the Isle of Bute
Ffordd pen llech in Harlech North Wales - now officailly the steepest road in the world at over 40% (it's a one way street going downhill!)
Gold Hill in Shaftesbury, Dorset - known as Hovis Hill after the iconic advert
Cote de Robin Hoods Bay - I'll probably need to do this at night (after closing time) as I don't want an audience if/when I fall off!
UTP
TMS