I think it depends who you speak to as to which is best, but they both seems to have a good reputation - I have had several people tell me either one or the other is the best place to go to. (Daughter rides at Welly quite often)
Did my 1 and PTT and Wellie. Was ok, although I didn't find the staff there friendly (and in my PTT flat lesson they stuck a dressage saddle on a horse that didn't fit from a MILE off! So I'd check your tack carefully!)
Did my 3 at Ryecroft. Both flat horses weren't up to standard (examiner commented). One was a cob on a mission that was green as a daisy and the other was incredible stiff and staff mentioned that he was always ridden in a double and not a snaffle! Great! Thanks!
If I were you'd I'd go to Pippin. That's where I was advised to go by an examiner that trained me. I went and looked around it, had my exam booked, and it got cancelled and transferred to Ryecroft. Grr!! The horses looked very good though and staff were brilliant.
Having had riding lessons at both places, for me, Rycroft wins every time. I'd not go back to Wellington again ever. I would happily return to Rycroft.