Close to home for all the reasons that have been suggested (especially making local friends) unless your working hours mean that you are likely to be late for work or (worse still) late for pick up (ours fines vey heavily, husband got stuck in traffic once, ouch!)
I've changed my start time at work as I have a 40ish minute commute by train and was regularly missing the one that got me into work on time. 8:00 drop off and 8:07 train over the road seems fine, but then suddenly toddler refuses to get into pram, or you have to sign medicine form because he's on antibiotics, or he's clinging to your leg crying and before you know it you've missed the train and late for work.
Our nursery is great at realising that you've got to make a move, but at the same time, you don't want to spend the rest of the day feeling like a shit mum because you didn't try to settle your distressed child (although they seem to do this entirely to induce mummy guilt, my son has grown out of it now, but when he was at his worst, they used to phone me 15 mins later so I could hear him happily giggling away).
With my job, I can only do local to home nursery because husband does 99% of pick up, if I had to pick up too, it would have to be closer to work.
The ill thing is a good point too though. I never suffered from stomach bugs pre-child, and thankfully it seems to have now passed, but there was a period when he was a baby/little toddler where he would either have a but of diarrhoea and a little sick (so off nursery for 24 hours) or just actually a slightly runny nappy and 2 days later I'd be floored by a horrible bug and just be so grateful that I could stagger into nursery and drop him off for the day.