For option 3 a flight booked in WT+ (Blue membership level) earns 4323 (LHR-JFK), presumably per direction. In addition the costs of £1005.85 would earn 1257 Avios at the 1.25 rate. Therefore this option costs 10097 Avios net. Assuming a CW fare was available at £1500 this would value 1 Avios at 4.89p. But you do have to spend over a £1000 for the ticket in the first place, which is not an insignificant sum.
Indeed, and that's why using Avios to upgrade from WT+ to Club World is generally seen as the best way to get value.
If you're comparing like for like, in the above scenario you spend 10,000 avios (because you get 10,000 back) and pay £1,000 for the WT+ ticket. For a straight redemption, you pay £500 in taxes anyway but lay out eight times the number of miles.
The thing that's missing throughout however is the woeful award availability. I looked at trying to get to a conference next month and there's nothing at all that comes close to being useful. This makes the comparisons even harder - it's all well and good saving up the miles but if you can' be flexible with your dates then you risk being disappointed anyway.