The horse that has impressed me most this NH season is JACK THE GIANT, a 5-y-o chaser trained by Nicky Henderson. I saw this horse make its debut in early November at Sandown. As his name suggests, he was an imposing type in the paddock and certainly much bigger than most 4-y-o chasers. He jig-jogged round the paddock but jumped the tough Esher fences impeccably and won well.
At Kempton, he won the Grade 2 Novices' chase despite having looked beaten two out. He clearly loves decent ground and jumps well. I'm NOT saying he'll win the Arkle but he's the best I've seen and if you can back him at a reasonable price AND they let him take his chance, he could go well.