Sexton has become a class player over the years. But I am not sure if he would have had the nerve that O’Gara showed towards the end of the Wales game in 2009. Then again, O’Gara had to work hard throughout his career to attain that level of nerve. I think O’Gara probably had to work harder on his game than Sexton would do now, especially on his defence. That said, although he wasn’t the best tackler, O’Gara still never shirked responsibility in the tackle. Sexton has great natural strength and speed and good hands but I think in basic footballing skills, O’Gara was that bit better. His cross-field kick in Croker for Shane Horgan’s try against England and his chip and chase for O’Driscoll, again against England, late on in Twickenham (was it 2004 or 2006?) that led to Horgan again, winning the game with a corner flag touch-down - I’m not sure if Sexton would have had that level of footballing skill.
Two other worthy mentions are Ollie Campbell and Paul Dean. It would have been interesting to see either of them in the professional era. Dean was a great passer, albeit a sh*t kicker and was great with the ball in hand.
Nobody mentioned above could match either Jonny Wilkinson or Dan Carter, for me.