From that list, Tan Hill straight after a fat-boy fry-up ... I like a handicap.
Must go and do Streatley hill, it's close enough for an out and back blast.
To others, yes I know a 1km 130m ascent doesn't seem much but it really does have an OMG factor when you turn off the A329, it is similar to the start of the Struggle when you turn off the mini roundabout in Ambleside at its start.
I haven't tried to cycle up it yet from that route, I am sure it is beyond my capabilities and there is a longer flatter route to reach the Bell Inn at Aldworth (and that is a pub any real ale drinker should visit) from where I live.
Also if you are travelling all the way from Abingdon, might I suggest a taking nice back country lane route through Ashamstead and Stanford Dingley to
this hill at Rotten Row out the back of Bucklebury and approximately due south of Streatly. I think it is worse (or better depending on your point of view) and definitely quieter.
Again I've not cycled up it, only walked it, on a walk I emerged halfway up it and thought, blimey, this is the steepest I have seen in the area, even worse than Watership Down. It is a genuine 20% gradient and still has a 1:5 sign at the top of it. I don't know of any other two chevron marked hills in the vicinity.
hope the information is of use
Peter
