So after hours and hours of research and experimentation I have now, I think, made sense of the tactical voting sites for #GE2019 
My complete review is here:
https://jonworth.eu/2019-uk-general-election-tactical-voting-guide/

My complete review is here:
https://jonworth.eu/2019-uk-general-election-tactical-voting-guide/
tl;dr - contrary to all the critique of these sites on Twitter, all the major tactical voting tools make pretty good suggestions in the majority of cases
But you want the detail, right?
I looked at 4 tools:
https://getvoting.org/ by @BestForBritain
https://www.remainunited.org/ by @thatginamiller
https://tacticalvote.co.uk/ by @lauriesutcliffe and others
https://tactical.vote/ by @ZoeJardiniere and others
I looked at 4 tools:
https://getvoting.org/ by @BestForBritain
https://www.remainunited.org/ by @thatginamiller
https://tacticalvote.co.uk/ by @lauriesutcliffe and others
https://tactical.vote/ by @ZoeJardiniere and others
I did not assess NI seats, but did assess all seats in 

(632 seats)
In 507 of the 632 seats, there is no difference between the sites - in these seats you can vote tactically with confidence (and amongst these are some of THE MOST important seats to vote tactically!)



In 507 of the 632 seats, there is no difference between the sites - in these seats you can vote tactically with confidence (and amongst these are some of THE MOST important seats to vote tactically!)
Of the remaining seats where the voting tools differ in their recommendation, 86 seats are safe seats for the Tories
In these seats you can vote for more or less whoever you like as a Remainer and it will have little impact (sorry, but that's life)
In these seats you can vote for more or less whoever you like as a Remainer and it will have little impact (sorry, but that's life)
That leaves us just 39 of 632 sites where there is no consensus between the 4 tactical voting tools, and *also* the seat is not a safe seat
My blog post assesses these 39 seats one by one
My blog post assesses these 39 seats one by one
3 of the 39 are special cases (Buckingham, Chorley, Don Valley)
In 2 of the 39 (Beaconsfield, East Devon) vote Independent
In 5 of the 39 (Bury St Edmunds, Colchester, Elmet and Rothwell, Leicester East, Macclesfield) back Labour
In 2 of the 39 (Beaconsfield, East Devon) vote Independent
In 5 of the 39 (Bury St Edmunds, Colchester, Elmet and Rothwell, Leicester East, Macclesfield) back Labour
In 16 (Altrincham & Sale West, Chelsea & Fulham, Cities of London & W, Eddisbury, Esher & Walton, Finchley & Golders Green, Henley, Hitchin & Harpenden, Newton Abbot, NE Somerset, Sheffield Hallam, SE Cambridgeshire, SE Cornwall, Southport, St Austell & Newquay, Woking) Lib Dem
In the final 13 (Broxtowe, Filton & Bradley Stoke, Hendon, Isle of Wight, Kensington, Luton South, Putney, Rushcliffe, SW Hertfordshire, Wantage, Watford, Wimbledon, York Outer) I need more data before being able to make a call


I welcome input and questions about the blog post and the thread, and additional data to help solve the 13 outstanding constituencies would be very welcome.
Essentially though the problem is not WHO to vote for, when voting tactically, but to get ENOUGH people to do so.
That job starts now!
/ends
That job starts now!
/ends
Please note: this blog post has now been updated to V2 in light of new data in the past 24 hours! A small number of recommendations have hence been changed!