Morphiza is a very nice little freebie from Krakli. It has a nice little GUI, not too may controls so the danger of getting incurably confused is rather low - and doing your own presets easy, has as starting point 16 good presets, no manual - nor is it needed, and cost nothing. It is supposedly styled after the transitor organs of the 70s, but since i don know the originals, i can say anything about the "quality of emulation" nor does that matter, cause it sounds anyway great - a clear and transparent organ with some "roundness" and character. It cuts through mixes well, probably works with every kind of music, uses not too much CPU - to put it other way: it is very good and usable ! Try it out, unlike many other SE synths you wont notice its heritage, and thank its author for making such a freebie.
Now here's a nice little organ VSTi, not often mentioned but capable of some very nice sounds.
This is an electric organ, so none of your classic B3 / B4 noises are to be found. Instead, you get a variety of (often cheesy) organ sounds that sound a bit like an old home keyboard I owned in the 80s. Also reminds me a little bit of Combosister (although it's less versatile than that). Don't let that put you off, these sounds are often great for lead lines and can cut through a mix really well.
It comes with a small number of decent presets, but if you want more it's easy to create them. It has a "reverb" which is actually a delay on its "long" setting, you can't vary the speed of it beyond "short" and "long" (as far as I can tell) but again this is all reminiscent of those ancient home keyboards. If you want tempo-synced delay, you can always use any of the dozens of freebies out there in your host.
There's also tremolo, vibrato and "swirl" settings to manipulate the sound, plus simple "tone" controls.
I couldn't find a manual but honestly, you don't need one. The author is often to be found in the KvR forum in the unlikely event you need support. As for stability, there's been no hint of a problem yet.
All in all, a really nice little free synth that's genuinely useful. I really like it.