I'm just an amateur and relatively new to film but have used a few different types of film and here is what I've found: Ektar is a really good film to use on overcast days, it has awesome green tones especially in foliage under canopy. It can be quite 'moody' in this kind of environment. Portra is really a really great all rounder (I've only used 160 and haven't ran any 400 yet) and I love the reds. It shines on sunny days but even in lower light it still works great. Reala is ok but probably not my cup of tea. It has a very strong "70s" colour tone to it (well the roll I shot, anyway) but I was not a fan of the latitude. It renders a scene in a kind of retro way which might suit some people. I have not processed any of my velvia or provia yet but should be in the next couple of weeks. It seems that most people in the know prefer to shoot velvia 50 if they can afford it (I paid $130 AUD for a box of 20 in 4x5 and around $65 for a box of 120) In saing all this I am leaning more towards black and white these days and am actually going to look forward to blowing through all this colour film I have and just sticking to tmax, acros and ektar/portra/velvia. I like acros especially for the reciprocity characteristics and tmax has wonderful contrast