Hi Adele! I'm a beader (usually the more complicated, little seed beads) and I have a lot of different threads, so hopefully I'll be able to help out :)
What size of beads are you using? The threads that you can use will very much be linked to how wide the hole is in the beads!
For what it's worth, I love C-Lon. It's a fine thread (under 0.5mm) and is fantastic for threading beads with smaller holes. It's also available in lots of colours. There's a wider diameter available as well for heavier beading!
For smaller, seed beads, I use Fireline. It was developed as a 'Fishing Line' so is very strong, durable and knot-free! It's a little on the expensive side, but it doesn't stretch like other beading threads.
I really hope this helps, but feel free to reply (or PM) if you have any questions! :)
<p>'My great mistake, the fault for which I can't forgive myself, is that one day I ceased my<em>obstinate pursuit</em> of my own individuality. ' Oscar Wilde.</p>