i never vent directly outside i vent from room to room, this makes it very easy for me to tell when filters need changing i can smell the outlet directly
i have budget and the more expensive filters
very little difference to be honest , just make sure you get the right size to cope with your fan
they last well over 1 year,
remember the filter is there to remove the smell from the air that is removed from the grow space, as most folk extract outside and do not wish neighbors to smell plants
some people make the mistake and think the filter is there to remove the smell from the room itself , unless you have the plants in a small sealed tent this is very unlikely, the filter is irrelevant to the smell left in the grow space other than how much the filter reduces the fans extraction, this is dependent on fan power, the faster you remove the air and replace it with clean air, the less you will smell in the space
to remove the smell from the room itself requires much larger fans to remove the air as quick as possible if you do not remove all the air in the space in less than 1 minute you will still smell it but this does not mean anyone else can smell it, as long as you control the air flow and create negative pressure so air only comes into the space and does not leak out, you will be fine
ozone works well to remove any left over smell in the grow area, but needs to be used correctly with caution
peace