Have a row of small format modules from Doepfer and another from Analogue Systems. Be warned that ASys modules do not fit side by side with Doepfer ones.
Doepfer are cheap for what you are getting and the number of modules he now offers is quite outstanding. ASys have a smaller choice, but there are some real gems in there. Some of the new digital stuff is very clever. They also make a nice phaser, but then I would say that because I built it
Then have a row of some of the larger format ones. Synth.com make some excellent value modules and look a bit Moogy which will always impress. MOTM modules are well built and have a big following. My favourite, purely on the point of sound and build is Modcan. I wish he'd gone for black panels on the B series, but they do sound good with a lot of interesting modules.
Cynthia offers Modcan A series compatible modules of all sorts of interesting types.
Depending on where you are the USD is very weak against the pound so buying some of the US built stuff is good value right now.
There's also a lot of other smaller companies that offer one or two modules. See the AH archives mentioned above for lots of other useful advice.
And if you can wield a soldering iron then don't forget the large number of self build modulars you can get too. See my web link for my stuff.
