Big Bang Orchestra by VSL is a tutti orchestra VST.
You have an orchestra with all the articulations you need and a few effects.
Uses the VSL Synchron Player(free) and loaded in as VSTi & VST3i.
Versillian Studios Chamber Orchestra 2 - Community Edition is a compact edition
that includes most standard symphonic instruments.
Available in multiple versions: SFZ, wav, VST, NKI,...
The Free Orchestra by Project Sam is a semi-tutti orchestra VST.
You have an orchestra with all the articulations you need and a few effects.
They are seperated in seperate groups and multis to have a certain vibe.
No individual instruments.
Uses Free Kontakt Player.
BBC Symphony Orchestra Discover by Spitfire Audio is orchestra that includes most standard symphonic instruments.
Some individual, some ensembles of instruments.
VSTi & VST3i.
Layers by Orchestral tools is a ensemble orchestral vst.
Containing groups of instruments(brass, strings, woodwinds,...) and a tutti orchestra.
VSTi & VST3i.
Virtual Playing Orchestra is a mixture of free orchestal content available.
Individual instruments with multiple articulations.
Installation is a bit tricky, it uses soundfonts and requires a soundfont player.
However installation is explained on the site.
Also you'll need to add reverb to the samples.
DSK Overture is a classic amongst the free orchestral libraries.
Contains lots of instruments.
Requires a bit of work to make them sound good.
VST.