When I started with photography in the early 90's I used FP4 and Velvia 50. Since 2011 I have been trying out various films, and there are definitely likes and dislikes.
For medium format, I'll use mostly Tri-X (my favourite), but all the Kodak and Ilford emulsions are good. I also use FP4+, which is probably the film with the best tonality and robustness all round. I stashed up on Acros when it cost $2.68 a roll, so that will also see me through whenever I can't get my first choices.
For 35 mm, I will use whatever I can get my hands on. It makes sense to me to use the same emulsions in 120 and 35 mm, as one has fewer developing combinations to deal with. For that reason, I don't buy Kentmere and Neopan 400 any longer, even though they are fine emulsions. Acros coupled with excellent lenses is wonderful because of its fine grain, but seriously, why does it need to be so expensive in 35 mm?
For colour (only 120): Ektar or any of the Portra films (160, 400 and 800). I probably use Portra 400 most often, as it balances speed, cost and quality. For slides, well, what are the choices? Basically Provia 100F. I have shot some Provia 400X, and it is/was a fantastic film. They should have stopped Velvia rather than Astia and 400X. Can't they just schedule annual or bi-annual production runs rather than stopping altogether? Oh well, such is the analogue life.
Dislikes: Anything with Lomo written on it. Foma in 120, because last time I tried it was so curly and difficult to load. Rollei RPX400 in 120 if I can't shoot and store it cold, because I get frame counters etching onto the film, and I think it has to do with heat more than light. Kentmere films, because they are never in stock at B&H when I need to order, and unavailable in 120.
I think Ilford as a company shows most commitment and the right attitude to survive in a diminished market. If they can't make it, nobody will. It is a pity they don't have at least one colour neg and one slide emulsion in their line-up, as it would have bode better for slide film in general if Ilford were a player there. Still, I'll happily support them whenever I can.