Can any of you synth aficionados recommend a good synth for usable bass sounds? 
 
Thanks - rev

Trilian.
 
https://www.spectrasonics.net/products/trilian.php

If you're looking for sampled basses, Kontakt has a bunch of 3rd party you can buy (some of them relatively cheap).
If you want synth basses, try Massive....
Are you looking to buy?  Free?  In CbB? 
 

This is free!
 
Ample Bass P Lite II
http://www.amplesound.net/en/pro-pd.asp?id=19

My first reaction to the OP may be a bit off-kilter, but a lot more samples end up being "usable" if tailored correctly. Rather than a search for pre-processed samples (which can get exhaustive and expensive), using MCharacter on the rawest signal possible (monophonic is best) and then feeding that into an FX chain afterwards has made a lot of samples I thought I would never use (ones preloaded with SONAR) "usable." What sucks is that was 50% off just a few weeks ago, so it will take some time to make another round on sale, but is a very useful "tone-carving" tool.

I use Element 2.0 from Waves. For me, it replaces all my other basic analogue style VST synths. It certinaly can replicate the 303 and Juno by Roland - both popular bass synths throughout music production over the last 30 years. If you want something more complex, I also like Waves Codex wavetable synth. You could create a bass sample or download a 303 grain which could then be manipulated to create a bass sound. Finally, if you want a real simple bass synth, I'm not sure if the company still exists, but there was, and I still have the free version from almost 18 years ago which was the Muon Tau. This is a proper 303 bass synth clone.

Ben

Rapture/Dimension Pro have some very useable bass patches.

Almost anything by Moog.

Arturia Mini/Microbrute.

A great bunch of suggestions, thanks to all.  I have some of those plugs but after hours of paging through the electronic barnyard, I said why don't I just ask someone. I've been doing this a long time but some of you have been doing it longer and some of you are keyboard/synth players, so I've learned to ask.
 
abacab:
You're right about Amplesound stuff, I do video tutorials for them in return for the software so I have ALL their virtual guitars and they really are the best - my next tut will be about the 'Riffer' feature which may not be included in the Lite version but it's well worth a look. In this case though, I was specifically looking for synth basses.
 
BTW: I checked 'Instant Notification' but I didn't get any notification. Is that happening (not happening) to anyone else?
 
rev

For Synth bass (EDM), NI Razor is very cool.