HP5+ is my favourite general-perpose film - purely personal, I know. I just like the 'feel'. Obvious grain but not too obtrusive. It's also very versatile. I've had excellent results at ISO200 in Perceptol (1+1, 15 Mins) - lower contrast and less grain , ISO400 in ID11 (1+1, 13 mins) - for general use and at ISO 800 in Microphen (1+1, 16 mins) all at 20C - 'grittier' feel, seems to suit Northern English landscapes! I generaly shoot 6x4.5cm.
OTOH if I'm shooting 35mm landscapes handheld, particularly if the sun's out I'll use Delta 400.
Try a few combinations and see what you like!