GTG Synths GTG FM4 by Music Bird
It has very varied presets. I was able to get a lot of tones ranging from basses to FM harmonicas to ethnic sounds in my tracks.
FM4 can do all sorts of stuff that most other FM synths can do. And it can cover bass perfectly. There are plenty of presets to get started on (about 64 of them). It has 8 voice polyphony and it can do the classic FM pianos and basses and sounds. The one thing I have a problem with it for is using it for programming, since FM is difficult to program. I made some nice shakuhachi and organish flute sounds using one patch and changing the pitch of operator 1. You can do many typical FM things.
The presets you get are varied and include basses, brass, flutes, guitars, keys, and leads. Also strings for good measure.
Ease of use:
You can get sounds very easily due to the nice interface of the plugin. It has the numbers on it already so you can get nice sounds. You can make all sorts of sounds easily with the interface.
Since I don’t know a lot about programming FM synthesis, I could say it has a lot of features. Most notably a nice LFO and some good patches with pretty much everything covered.
Bang for buck:
It’s free. So you get a lot of good sounds.