Well, if instead of a drawn out game with actual well... roleplaying, you are just using the D&D rules for some sort of arena match....
Naturally, you should always use the race that naturally enhances the abilities of your class. And the classes tell you straight-out which attributes you need and you can just match those to a race.
Although there was more effort in this edition of D&D than in any previous edition to make it so that if you didn't choose THE stream-lined and ideal race for your class, you still derived things from the race that benefited you (in fact, even better, the first couple races designed actually have traits that either become obsolete or extraneous if you choose the "best" class for the race), the Half-Orc was probably the worst designed with such a goal in mind.
The half-orc's abilities only really kick in if
a) You are a melee fighter who uses a weapon (primarily strength based)
b) You are liable to take damage before anyone else in the party and at risk of being knocked out.
And a lot of the "investment" you make in the race is in a. Sure, I am not accounting for the bonus Intimidation skill, but you are free to get that with any class.
The fact that the Half-Orc is designed exclusively for a class that is a strength-based melee fighter who is more liable to reach 0 HP before the rest of the party, really, truly limits the number of classes one can even attach the Half-Orc to and receive any meaningful benefit. Particularly in an edition that was so very much concerned with making Dexterity-based Fighters a viable thing that they over-reached and made the traditional Strength-based ones basically crap in comparison.
Unless your character is a Barbarian or a Paladin, there is absolutely no reason whatsoever to choose the Half-Orc if you are trying to make an effective character in battle. You can use the race to make the inferior Fighter build marginally less inferior, but only marginally so.
Although- if you were running your campaign to level 20, then the fact that mystic can be a melee warrior and tends to be lacking in both HP and AC (two things making it more likely you will be knocked out), it isn't the absolute worst match-up for the Half-Orc race. So if you were going to be high enough level to guarantee through attribute increases and magical items you would reach the score of 20 in your primary attributes regardless... you might even be doing better than a High Elf one.