As far as good masks go, I suggest hitting up a paintball shop if you've got one nearby, and just trying on everything they have. Pretty much everything with a thermal lens is good, but the different brands will fit your head differently, so finding one that fits you
best is important.
Toss 'em on, shake your head, look down, look up. Does the mask move well with you? Can your breathe well, and hear in it? Is the field of vision good?
A well-chosen mask is far and away the best place you can put money into your kit.
As far as guns go, consider the ongoing cost as well. Playing 24 BPS with the Reflex means about 75 cents a second worth of paint, if you're paying $60 a case like I am here. That adds up quick, so speed of fire may not be the best thing to use as a deciding factor.
Play how you want to, but if you can't afford to feed the gun, you're not going to get as much use out of it as you could, and 12.5 bps is just as workable as 24 for most things. Don't give up something that fits your hand and pocketbook better just for gofast.