I have an equigel that my saddler has lent me as my horse has lost weight since he had his saddle fit. It's good because it's not gel along the centre so tucks up nicely in the gullet of his saddle and doesn't press on his back.
A prolite is the only "gel" pad I use. My old oss used to use the gel pads you can get from horse health wessex, they feel lovely and dont adjust the fit of the saddle as the dont make the gullet narrower?! But I stick with a prolite or a sheepkin pad
Prolite - they are by far the best. Easy to look after, never puts pressure on the spine, does not slip and they only need replacing every 5 years or so.
Prolite everytime. I have just treated myself to a new one when I realised the one I was using was now nearly fifteen years old! They are just the best I have to say.
if you cant afford new you can pick them up for £30 used on Ebay.