As above, only ever used Hope clamps so no experience of the Thomson ones (I do use Thomson seatposts). The Thomson looks a little neater so which one?
Or salsa
My silver thomson clamp cracked after about a year
It wasn't a qr so it didn't get any real use, other than keeping the seatpost In place.
Salsa are about the best I've ever used, wasn't impressed at all with the Hope one I used previously.
I always used Hope QR clamps,but if the post is a loose fit they need a huge amount of lever pressure to stop the post slipping. Salsa clamp has a longer lever & is also easier to use.Also the Salsa clamp ,both qr & allen key have a larger clamping area.
Salsa works just fine.
Hope works just.
I'll be the first......... Chromag.
Salsa all the way. Absolutely no competition.
Chromag or Salsa, both are excellent and beat the other two you mentioned hands down.
Salsa all the way. Absolutely no competition
It's good, but it's not right, says Roy Walker
I'll be the [s]second[/s] third......... Chromag
Rather spendy, though
Thomson are good for reverb as low torque
Salsa- good if you want QR and are portly, like me (19st-ish in riding kit).
Thomson or Straitline if you don't want QR and are portly.
Hope gave up against my enthusiastic mass.
Oddly Salsa non QR slipped on the full Paris Roubaix, but a big day out with over 55km of horrid pave on 90 psi tyres was never going to be easy on the bike.
I've got a Chromag and it's great, but I do have issues with it creaking unless the brass bushing is liberally greased.
Salsa are by far the best I've used. Hope are truly horrible, very crude in comparison.
Chromag. Job done!
Yeah salsa here no comparison
Hmm, don't want qr, that's the reason for changing the Orange Strange qr that I have on my Clockwork at the moment. Need a flush fit at the top tube/seat tube junction for a bike packing bag.
Salsa non qr looks good, what size will I need on a 2014 Clockwork, 30.9mm seatpost.
Oh, not qr - then anything that fits and you like the colour of 
Personally, Salsa or Thomson if I'm looking for a non-QR clamp (ie, if I have a dropper) - Thomson for preference but Salsa if I want ano.
Salsa or possibly Chromag if it's a QR.
If there's a Hope already there, I'll use it with a drop of oil on the brass, but I'd probably not go out of my way to buy one. The hubs are good but everything else with the Hope name on is a bit overrated IMO.
+1 Salsa Lip lock
Salsa has been spot for me, great design.
Some folk reckon they wear out because the don't have the brass surfaces on the cam. So once the anodizing goes they get stiff. Mine is 3 year old on my most used bike and is still fine so not sure if it's a real problem. It might be if you want to adjust your seat very often.