there are a number of oldies but goodies I really like for analog ITB and as long as you don't care about powerful bass (or you're slick enough to doctor up some thick bass) they can go toe to toe with hardware in the mix. here's my go to plugz for fake analog:
blaukraut charlatan... very analog sounding. Bright and tight like my Dave Smith mopho. Sounds more convincing in DCO mode.
TAL U-no (reeware version)and Elektro, a juno6 and bass station respectively. U-no is particularly rolandy and I'll use it over or with my MKS50 rack (which is more of an alpha/106 sound)
All the elektrostudio plugins. They don't sound perfect but they sound good. I particularly like the mellotron and use it all the time. Its even on my muse receptor for live performance. I'm also known to mess with the moog prodigy one, the other ones sound less good to me, but aren't BAD
The couple of free U-hes are great, although they have very limited applications
NI's free reaktor stuff? of course it sounds great. Mikroprizm is the most unique and therefore most useful. The blocks one does stuff that Ic an't get my eurorack and semimodular hardware to do, although its not as much fun to play with. There's a couple of other ones I've enver really used other than to try but they sound good.
everyone should have synth1, its based on a nordlead, it sounds just as odd in its own way, but its loaded with features with a really obvious architechture and if you're new to making your own patches its a good place to learn
Digital Suburban DEXED. DX7, simulator and patch editor if you happen to own a mk1 board (and everyone should, they made enough in the 80s for every musician to get one). Not analog, but DX7es rule. Nuff said.
Fullbucket music. My favorites are his Korg Monopoly and 3300/3200/3100 but all of his stuff is pretty damned solid.
SQ8L is a faithful copy of the ESQ1/SQ80. I have an ESQ1. Its getting unreliable. This gets pretty close. The model of the analog Curtis filter used in the original keyboards isn't quite there but at modest settings its nice. The waveshapes are bang on. Programming is just as nutty as it replicates the whole menu/button system of the original ensoniq synths. May be tricky for guys who never manipulated a real one.
Gluereeds is a physically modelled Wurlitzer electric piano that sounds more convincing than the other big freeware EP, MDA epiano (which along with MDA's piano is licensed by imageline for the fruity piano native plugin). The tradeup is that it has no controls apart from velocity scaling. Its a like it or lump it sound. I think it sounds as good as pay plugins like lounge lizard and have used it over lounge lizard many times.
Superwave. Its a JP8000 VST. Ya want supersaws? bang. Jst as lame sounding as the analog modeler it simulates with a few extra tricks up its sleeve. I don't actually use this one, I don't like the ubiquitous supersaw trance elad, but if I didn't have the ability to do that sound with my prologue now I oulda turned to superwave. It probably does it better than the prologue's supersaw digital oscillator voice anyway, the prologue analog filter soudns too classy! a real JP8000 sounds palsticy and weird. Its a glorified computer with keys so why not let your computer fill in for it.
a lot of freewares are made with synthedit and people just port in other people's filter coding when they need a filter so there is a 'samey-ness' to most freebies that were made that way. None of the analog fakers I put on my list have that homogenous filter sound. Each ahs its own voice, realistically analog or not. Just a headsup, until recently all the imageline/FLstudio synths and effects with resonant filtering suffered from this homogenous filter sound where they added a bunch of fitlers to the sampler module about 20 years ago and then just reused those models in many of their synths and insert plugins with filtering so it gave the whole DAW a really samey and boring sound, but they eventually got it after sytrus and started developing new code for every synth.... I digress
When I'm working alone I will a lot of times go for these plugins to create 'draft' sequences in the box and then replace stuff with analog synths from my collection as the song gets completed. If hardware doesn't sound any better or if I'm looking to use hardware to do soemthing exciting and unpredictble but the gear doesn't blow my mind? I use the plugin. Sometimes I double up very simialr patches with a peice of hardware and a VST and pan 'em out too. I have a huge affection for freeware. It end to think the VA
as toyour original statement? can't configure convincing soudns with the stock plugs from your DAW? Spend more time with them. The stock stuff in Ableton and FL can sound amazing. I'm an imageline guy, been with FL since it was fruity loops in the late 90s and the standout included plugins are SYtrus, Harmor and Harmless. But they're complicated with huge GUIs. Sytrus for all its graphical help is like an extra complicated DX7 with filters and effects (SY99ish) and you need to spend awhile learning FM. Even the stuff I just gave you won't kill you out of the gate, the hardware emualtions? you need to know that old gear a little. THe presets are generally crap :-)
sorry for the lack of links, use google