Here's what I use in my template. My template is inspired by John Williams's 'Hook' and 'E.T', just so you know what kind of sound I try to get.
Strings:
Cinematic Studio Strings is still the most convincing library on the market because of it's legato. Only downside is that the audio engineering isn't very good. The amount of players is a bit too small for a full symphony orchestra, so I strongly recommend layering it with another string library.
For layering, I suggest Spitfire Symphonic Strings (Now SSO). Has a lot of articulations available and the sound is lovely if you use the right mics.
If you're going for realism, I suggest you get a library with multiple string sections recorded together, to add underneath your other strings. For this purpose I use Albion One or Abbey Road One.
For chamber strings, I still think Spitfire Chamber Strings has the most beautiful sound. It's legato is good enough to work with.
Can't make a good recommendation for solo strings, because I only own Cinematic Studio Solo Strings. It's good, but I don't know if there are valid alternatives.
Woodwinds:
Cinematic Studio Woodwinds has offers pretty much everything I ask for. Good clear sound, convincing legato. Heard some good things about VWinds though, so check that out.
Brass:
Cinematic Studio Brass and CineBrass are both excellent. It's worth it to use these two together if you get the chance.
Alternatively, Abbey Road One Orchestral Foundations, supplemented with Thematic Horns and Thematic Trumpets, has the near perfect sound for scoring, but you're limited to horns, trumpets and low brass with a very small articulation set.
Percussion:
I know I'm starting to sound like a Spitfire advertisement right now, but Abbey Road High Percussion, Low Percussion and Metal Percussion are hands down the best percussion libraries I've worked with. It nears perfection, if you ask me. Huge array of instruments, huge amount of dynamic layers and round robins, and the sound is so good that they put some of my other libraries to shame.
When it comes to tuned percussion, I suggest Soniccouture's Orchestral Chimes, Celeste, Marimba and Vibraphone. Bit on the pricier side, but it's worth it. Just make sure you get a good reverb such as Seventh Heaven to blend it with the rest of your orchestra.
I've burned through nearly all the harp libraries on the market, but I've recently bought World Strings Harp and I highly recommend it. Very flexible with a good amount of articulations.
Jazz Big Band:
Can't recommend anything.