It depends what you want to get out of it. Different martial arts have different strengths and weaknesses based on what their objectives are. You have sport-based ones which are geared towards winning rule-based competition, which means lots of practice with legitimate technical application of what you're learning (good), but no practice against armed aggressors, or 2-on-1 situations, element of surprise or other factors (bad). Then you have self-defence-motivated arts which are geared primarily towards teaching techniques to be applied outside the place of learning should they be needed, and against all sorts of attack-types and situations (good), but limited or no sparring because of greater risks of injury involved, requiring a certain amount of cooporation between practitioners (bad). Then you also have arts which are traditional, 'set in stone' arts passed on as-is, such as with Japanese koryu arts.
In order to decide which art is best suited for you, you have to analyse your goals in learning one and then compare it with the ones that are available in your area. Benefits from martial arts training include fitness, self-discipline, personal/mental development, self-defence, etc., but the arts available will meet these benefits to different degrees. On the one hand you might have krav maga which trains against assailants with knives and firearms, but which can't allow full application of technique while training (because they include joint-breaks and injury) and might have to be significantly toned down (it's legally risky to permanently injure a guy just for shoving you), and on the other hand judo which is incredible for fitness and learning how to throw people, but which usually does not train against punches.
Your height won't matter hugely for almost any art you pick - don't let that be what makes your decision about what to learn. Height is usually an advantage because of your longer reach, but may not always prove so (for example in aikido, or in certain jujutsu styles). My advice would be to see what's in your area and then look up some YouTube videos on them to see what you think.