I can’t imagine not using Renoise, but there was a time that we all had to. What did you use Prenoise?
I was an Adlib Tracker 2 junkie, but made the switch since I could create more versatile FM style music in Renoise. I still fire up AT2 up every now and then to listen to my old stuff, but haven’t written on it in years. It was a really fun retro tracker once you got used to it.
Brendan
FT2
Cheesetracker
Renoise
I have tried all other kinds of things aswell. Including Buzz, Skale, FL, Cubase, etc.
Unfortunately… Renoise is currently only thing that suits my needs. 
this one did come along earlier…
aw what the heck, I like to spray my tracker history, because I’m proud of it
I began on the Amiga With OctaMED, but didn’t like the interface.
Pro tracker was my partner very long.
I wanted to go deeper so I bought Digibooster Pro (really good Amiga tracker)
but when things got more serious I had to find something else to use my hardware with. Amiga died so, what would you do.
I tried Fasttracker, but was more outdated then Digibooster Pro.
So I ran it emulated on my PC to get the reverbs and stuff reall time.
I was stuck…
then,BANG! Renoise 1.27 came out.
I used FLstudio 5, Reason.
Renoise is my bitch now.
I love her.
She makes me happy.
Made a couple mods on an Amiga and a 286, I don’t remember how.
FT2
MadTracker
Renoise
OS X Renoise
OS X Renoise is important because migrating away from Windows for me was inevitable. There was a few months when I had both Windows and OS X and there was no Renoise for OS X. I would fallback on MadTracker more than Renoise during that time. Had the OS X port not come along I don’t know what I would have done.
Nothing
unless you count like the 5 hours I spent with psycle. Not a bad program by any means, but I dug renoise’s gui and it was available for mac.
(PC) MED soundstudio
Fr00ty L00pZ
well it’s a good job you discovered the great renoise,
I’m talking for UK here, but when i think of fruityloops, i get the picture in my mind of teenagers making that awful ‘donk’ music.
music2000 (playstation) for three wonderful years
fruityloops for about 2 months
ableton
renoise - god knows how i found it - never heard of trackers before v1.8 but i instantly picked it up - have tried others since but never been able to use them in anyway near the way i can with renoise
fooled around lots, but started somewhat seriously with fruityloops. then moved to ableton and used that to this day as my main tool (with renoise). then i got into cubase for more professional mixing type stuff, and to track live off the floor. picked up reason more as an instrument than a sequencer, just send midi to it and audio out and such (or rewire).
I started on Amiga using Noise- and SoundTracker… StarTrekker… then MED V1. A loooong long period using OctaMED V4 (which was awesome and quick to use, plus had MIDi-support and builtin-soundsynthesis). Then for a few years I used Amiga SoundStudio for MIDI-stuff which had it good and bad sides, and later on tried pc-trackers like SoundStudio, FT2, ImpulseTracker, Buzz… which all are/were lousy excuse for trackers. Aside these I also did quite many tunes on THX2 aka AHX.
Its been a long and interesting 20-years voyage in tracking. Notable is that I never used ProTracker except tried them when a new version came out. All versions were unusable for me and I always went back to MED/OctaMED.
In chronological order:
Fast Tracker II (1996)
Impulse Tracker (1998)
Fruity Loops (2000)
Psycle (not for long)
Reason (not for long)
Buzz (not for long)
Renoise (2002)
Nuendo (2006)
What!? You didn’t stop at Renoise!? 
Actually Renoise is still my main sequencer. Nuendo I just use when working on styles more suited to traditional sequencers ie: orchestral.
My first app music composing application I ever tried was a demo version of Scream Tracker from a friends music magazine. Did not understand how to use it, but eventually we worked out how to load a sample. Hehe, those where the days. 
Then later some years I got addicted to Impulse Tracker. Never got into the Fast Tracker program, only used it a few times.
Then few years ago I tried Renoise, and it was quite good, but still it was not the same feeling like IT had. So in frustration I wasted my time trying to learn FL Studio… Sad but true I could not find FL intuitive enough to use my time in.
1 month ago I came back and tried Renoise again, and I must say its been improved alot since last time. I like it, and probably will stay with it for years to come (i hope). 
The tracker usage mileage for me starting from somewhere around '86
C64
Rockmonitor 3, 4, 5
Digitracker
Soedesoft Editor
Music Assembler
Also used Turbo assembler routines, but they were not surrounded by a fat ass tracker-gui.
Amiga
Noisetracker
Protracker 2, 3
Audiosculpture
OctaMed
StarTrekker
Oktalyzer
A few i forgot…
PC
Various lousy mod-editors (speaker only crap) including FastTracker 1 (that was a big piece of shit)
Screamtracker 3
Fasttracker 2
Impulse Tracker 2.06 -> 2.15
Renoise 1.28 -> Renoise 8.0 (by that time i’m already retired)
FT2
Skale
Renoise
Stairway
to Heaven
ProTracker -> ScreamTracker 3 -> ImpulseTracker 2 -> renoise
I’ve experimented with several soft but most of them are not worth mentioning.
I started with SoundClub - a freeware sequencer written by some Estonians. (actually I started with 2 cassette recorders)
After that I tried making music with cooledit by chopping samples.
So there was a bunch of programs I tried out after that, and ended up with Reason witch I used for many years.
Then I realized how pointless is to keep piles of refills on my hdd for one program. And if I made backup of my songs and all those reason refills and samples, after format it was a total nightmare… (who ever has used reason for some longer period, knows what I’m talking about…)
Now I’m very satisfied with having Renoise.
Also I use Ableton Live as well but it just a “tool” for me.
What the heck are those last 3? Never heard of those… Or I just don’t catch your humor.