I had started to rework the guide at the beginning of Preseason 8. At that time choosing the Precision tree with Lethal Tempo as keystone rune and secondary runes from the Resolve tree was the most recommendable (the AP build was a nice surplus which caught many opponents on the wrong foot).

It soon turned out that Fleet Footwork as keystone rune was more recommendable (everything else stayed the same). A little bit later some experienced players developed a strategy were you regularly invade the enemy jungle to consistently steal top buff - if you later don't need Smite anymore you could change it because of Unsealed Spellbook as keystone rune (so you have to choose Inspiration as primay tree) - with the upcoming changes to the Inspiration tree this strategy will IMO be less favourable.

Currently, choosing the Resolve tree (with Grasp of the Undying as keystone rune) and taking Precision as secondary tree is working very well (what I can tell from personal experience regularly playing Tryndamere) - the build just needs a little bit of fine tuning but works also quite well (later items are of course depending on the matchup and how the game goes).