Just pulled the trigger on a Seagate ST1000LM014. Amazon UK sold out but one of their Fulfilled vendors had just 10 left in stock. Seen enough comparisons online now to form the opinion that an SSHD hybrid drive is the best compromise. Near SSD speeds, still much faster than the normal HDD, but considerably cheaper than the SSD too.
I realise the 1TB version has a 5400rpm spindle, whilst the 750GB version has a 7200rpm spindle, but the 1TB version also has double the cache, and is a newer drive, so I opted for that instead. An extra 250GB storage can't hurt either.
EDIT: See post below, swapped to a HITACHI Travelstar 7K1000 1TB 7200rpm (32mb buffer) instead.