If I was buying an only vehicle now then I'd probably opt for a TD5, although my 90 300tdi CSW would probably be fine if it had a disco transfer box, but I own a car for any long/motorway journeys. The one time I used my 300 to drive 150 miles, then 150 back, to Silverstone full of camping equipment and a passenger and on the journey there kept to about 55/60mph, then on the return was in a bit of a hurry so kept to 65mph and averaged just below 31mpg for the journey which I was pretty pleased with. Admittedly it wasn't exactly relaxing but it really wasn't too bad.
As others have pointed out, the older, noisier, slower engine should be cheaper to fix but more of a chore to drive, and you'd probably have to work a little harder. The newer, quieter, quicker engine is more expensive to fix, but would be a much easier thing to drive on a daily basis.
Won't lie, I jumped into buying a Defender a few years ago and had only ever been in the TD5 pickup at work which never went over 25mph. I was very shocked driving my 300 home, but have got used to it and am a generally happier person when in my Defender when compared to driving my car. Most of my journeys are on A/B roads though and not on any excessively busy or fast roads. Bought it for it's simplicity, rarely regret it, probably wouldn't regret owning a TD5 as there's a mechanic in the family who could sort me out.
