I think it all has to do with personal preferences. The long range guys tend to prefer 1st focal plane since regardless of zoom their mils/moa are consistent. For the average hunter, the generally less expensive 2nd Focal plane works perfectly. Within most hunting shots, you'd be hard pressed to tell the difference.
Practicing shots at different ranges and different positions is more important than focal plane.
If I'm using the reticle for either drop or drift I strongly prefer 1st for the reasons stated above. If not then I'm pretty ambivalent, but one could make the case for either depending on the situation.
Depends on power range for me. Anything over 15x I prefer FFP. Anything at or under 15x SFP will suffice. If you dial for both wind and elevation, you're reticle can still be useful in a SFP when it's not on max power. The hash marks may not have their full value but can still be used for hold offs
First or Second focal plane also depends some on manufacturer. If you have an opportunity to look through both from the manufacturer of your choice It's definitely worth it. With a higher power long range scope, a FFP is a real benefit. Both at higher and lower powers. At lower powers, you have heavy side bars that help you to pick up the reticle quickly especially in low light, or in timber, but you still have a very fine reticle at high power that will not obscure a small target.
For most hunting situations, 14ish power or less and ranges less than 500 yards a second focal plane will work fine. I typically use 2fp reticles, but would really want to go to a FFP for any more precision or long range work. I've had problems with the reticle on my 4.5-14 Zeiss conquest with their RZ800 on steel at 600yds plus. The sub-tensions of the reticle get quite large on small targets at long range... I also had a Nightforce NXS 3.5-15 with their NP-R2 reticle, it was rather dificult to pick up in timber, and in low light when un-illuminated. But, the sub-tensions of the reticle worked far better for precision work.
For a long time I drooled over a FFP Nightforce, but just couldn't justify the $500 price jump when I got mine.