Hi Mollo, I think Lisvna is right in saying it mostly boils down to each woman's experience but there's also good clinics and not-so-good clinics. There are many reasons for this (how good the doctors are, the equipment, the care, the qualification of staff, pre-ivf screening and medication...the list is long). The best thing is to do a lot of research, talk to the doctor, the staff and other women who have been treated there - with both negative and positive results. It is too much of an expensive and emotional undertaking to choose a clinic because it is less expensive than other clinics. And if it doesn't work the first or second time, then you need the assurance that it wasn't because the clinic didn't do everything they should have done.
HRC and other US clinics: Medical costs are generally very high in the US which accounts for the high IVF costs. But, from what I have read here on this forum, HRC also orders a lot of pre-screening tests and prescribe shots/medication that other clinics do not. They have a round-the-clock service and the equipments are state of the art.
Reprofit: I have heard mostly good things about Reprofit. One thing that concerns me, however, is whether they do much pre-screening at all - which could really affect the outcome of your retrieval and egg response/survival and thereby success rate. They also don't "officially" do GS.
Cyprus: I have also heard not-so-good things about North Cyprus and Dogus. Again, their fees tend to be a bit lower but saving a couple of thousands is not worth doubting whether you're in expert hands or not. I have heard very good things about Genesis/Dr. Savvas and I would definitely consider an IVF there especially if it's closer to my home country than the US.
That said, you can have good luck at the not-so-good clinics and bad luck in good clinics. Choosing the right clinic is not always easy but the decision can increase - or decrease - the chance of success.
(Personally, I'm waiting to see how it's going with Lisvna :-)). Will certainly help my decision-making)