If this is a PTMP setup I would opt for the 19dbi sector antenna. Unless you have an extreme lack of space,
or if you are setting up a close-range network (you wouldn't be asking about max distance if that were the case),
then it's worth going for the much useful extra 4db of the
mANT 19 paired with a
NetMetal 5SHP.
do you have any idea what would be the maximum distance does the Netmetal 5 partnered with Mant15s can reach?
That depends on what's on the other side.
If you're connecting to your configuration via a
LHG XL 5 AC,
then according to the
Mikrotik Calculator, and the specifications of all involved devices,
you can expect to obtain VHT MCS9 @ up to
6km.
Obviously this is half duplex, and obviously it is not going to be easy to replicate this result in real life due to environmental and other imperfect factors,
but even if not fully attainable you should still have quite a respectable outcome.
That's for full speed. If you are happy with a more modest MCS7 (144mbit @ 20mhz)
then according to the calculator, you can hope for up to
13km
But if you really do mean
maximum distance (disregarding the fact that your connection will be at basic rate and of limited if any use), then according to MTik you are looking at 200+ km with this setup.
Hope this helps