Interesting post from Vanilla. Different experience for us.
We used to be with VHI until 2002/2003 . From OUR experience (note the OUR), we never dealt with particularly friendly and helpfull people, we add difficulties with most of our claims, (wrong amount to a lesser value reimboursed, being told we were not cover for such case which turns out to be untrue and took months to settle, long dealy in payments, etc...).
Then opportunity arose to switch to BUPA (as it was called at the time) as part of new employment contract...and never ever had any complaint what so ever about their staff, claims, etc... Never looked back.
As for prices, IMO, BUPA is slighly cheaper, but i think there is very little difference amongst the 3 players.
Note: it would be fair to state that, to date, we never had to use neither VHI not BUPA/Quinn cover for major procedures. The most would have been to maternity level with emergency delivery.