Neither. I just think that he'd be a new broom as opposed to several of the others who have been around for so long. He has also had to build internal coalitions as regards the issue of additional powers for the devolved Welsh government. As I said, don't know enough about Leadsom to make a sensible judgement.
Hmm - let's not forget that the winner will be PM, not, as is usually the case leader of the opposition, with perhaps 5 years to gain experience and then only becoming PM if they are sufficiently credible (or not) to win an election. The latter being the case for Cameron, Miliband, IDS (although he never made it to lead the Tories into an election), Howard, Corbyn (see also comment on IDS - let's hope), Hague, Kinnock etc.
Do you really want a PM come September - in these most testing of times - who is woefully inexperienced, having only been an MP for 6 years and a member of the cabinet for 6 months.
Now is no time for inexperience - much as I cannot believe I am saying this, the only sensible choice is May.