Just going to throw my 2c in here as I tend to splash a lot less cash on VST instruments than on effects I have been only slowly building my collection. the one synth that I use all the freaking time however is the first one I bought: Synthmaster2. It is just great. thousands of presets, lots of options, and each version gets a little better with the UI. I also bought SynthmasterOne and just yesterday got Sektor for 14 bucks on AudioPluginDeals.com. Both are wavetable synths but have different sounds. SMOne has all kinds of sick modulation available like AM, PM, FM and in parallel wavefolding of all kinds for each of it’s two oscillators. It is a tad frumpy looking with the default skin, but the sounds it can produce are nice. Sektor is a bit more eye candy and has f.e. MSEGs and a few more modulation options plus a sequencer that SMOne does not have. for 14 bucks it was a no brainer. The sale is still on btw.
Also a big +1 for Bazille. What a freaking beast that thing is. Same with Iris2. It is a bit of a CPU hog tho.
Other than that, I use Hybrid3, Minibit, VaccuumPro and for drums Geist2 and Tremor. All these are good workhorse synths imho.