Is there a reason for Titan not being on your list?
http://www.kitz.co.uk/isp/isp_info.php
Or does it come under another name?
http://www.titan-adsl.co.uk/
Its purely because titan are a reseller. Most of the smaller ISPs are actually vISPs (virtual ISPs) who resell other brands such as Enta or Tiscali or Be etc.
Titan are actually listed on this site under
Entanet, although I think they may resell some others too.
>> Over at DslZone they seem to be rated quite highly.
If you look into it... the owner of dslzone has quite strong affiliations and associations with Enta.
Off the top of my head I can think of only one [edit 2] other broadband sites that doesnt have affiliations or ties when it comes to recommending ISPs.