Often the two largest factors appear to be size of the ISP and whether they offer what appears to be too good to be true, i.e. huge or unlimited download allowances at a very cheap unsustainable price. All the ISPs I have been with since the the 90s are still in existence, though some have been taken over by larger ISPs and I left them for reasons other than their demise. I am now with UKFSN which is one of a number of small reseller ISPs that uses the ENTA broadband wholesale service and being a part of the ENTA group have the advantage that they have a well established company behind them which is not purely dependent on broadband for their revenue stream. It also has the advantage that if UKFSN, heaven forbid, did actually go belly up I could make a near seamless transition to another ENTA reseller or get a MAC and migrate out of the ENTA group completely to another ISP.
It is very likely that quite a few of the smaller ISPs will either go out of business or get taken over by larger ones in the next few years due to the small margins for ISPs dependent purely on broadband for their revenue stream. Thus it is often pot luck whether a small totally independent ISP you join now will exist for any length of time but looking at the type of packages against price that they offer as well as their history can often give a good idea. Additionally, if you prefer the smaller ISPs look for a good small run one that it is more likely to get taken over than go under. These forums are good for keeping an eye on how an ISP is developing or not. That way at least, if after being taken over the service deteriorates, my reason for leaving the last two I was with before joining UKFSN, there is usually no problem in migrating to other ISPs and in each case I migrated away from the deteriorating ISPs with no down time. Though I also always look for ISPs that have only a rolling monthly contract so that if I am not happy for any reason it is relatively easy to migrate without incurring cost penalties to get out of restrictive long term contracts. Additionally, new OFCOM rules about the issuing of MACS are coming into effect next year making it more difficult for failing or deteriorating ISPs to hold their users hostage by withholding MACs or procrastinating on issuing them. .
EDIT: Typos
Edited by deleted (Mon 25-Dec-06 10:38:34)