Fundamentally you need the capacity to enter into position to
apply your system's methods, and the methods need to be dominant
from that position. That's a mild restatement of force the opponent
to fight "your fight", and be better at "your fight" than your
opponent is. The discussion below starts with empty hand since that
tends to be what people think when the term martial arts is
used.
Muay Thai is an example of an excellent art. It has very
powerful fast long range kicks that are very difficult to close
against. If you cannot bridge the distance against a good Thai
boxer (not an easy thing) then you can expect to take quite a
bruising.
Another example is modern free style wrestling when combined
with an effective ground submission system (sambo, bjj, "ground and
pound", submission wrestling, etc…). Freestyle wrestling provides a
strong capacity to bridge the gap in the form of its shoots, and it
has a range of extremely effective takedowns.
Another excellent art is Yiquan. It has excellent lateral
mobility and strong standing strikes and throws. The extremely fast
lateral footwork gives the Yiquan practitioner a good chance to
bring the fight to stand up fist fighting range, and their powerful
hand methods often allow them to dominate once their favored range
is established.
For "short" bladed and impact weapons I would recommend an
established military system like Pekiti Tirsia Kali or perhaps the
Systema that is associated with Mikhail Ryabko.
For long weapons, the Northern Chinese Liu He spear, Miao dao
2nd form, Feng Mo Gun, and whip staff are all first rate.
