I like Alan Tichmarsh on gardening programs. Not so keen on him as a general presenter though. Strangely I really didn't likle Monty Don on Gardener's World for some reason I felt like he was always talking down to the audience. Then I saw him on the program about great gardens of the world and he was perfect on that. He was knowledgeable, erudite and enthusiastic; he seemed like a different presenter.