Wow, I have much admiration for you for battling through all what you have encountered, that takes guts and strong will power.
I'm not going to say which art is best and which is worst, it depends on a number of factors. Those being; the practitioner, the teacher and your initial goal. There is no such thing as a good or bad, or effective or ineffective martial art, they all have their benefits!
Size and strength plays little to no part in aikido. It's a non agressive martial art in which you can't use it to attack people or harm them. Aikido will help increase your awareness of surroundings, improve reflexes, concentration and agility. Aikido is also a non-competitive art (unless you wish to learn tomiki aikido) mainly consisting of throws locks, pins and focuses on blending with the attackers momentum and re-directing it. I think compared to the other arts you are looking at aikido has a low impact on the body, we've had many karateka join our club because their joints could no longer take the battering they were enduring.
Depending on what club you join, most of them incorporate weapons work into their curriculum. We use a bokken (wooden sword) a jo (4ft wooden staff) and a tanto (wooden knife) the latter being used to practice against knife attacks. Most if not all movements in aikido derived from the use of the sword thus the reason why we practice with a bokken. At our dojo about 80% is open hand technique and 20% weapons work.
I would suggest attending an aikido dojo for a few weeks so you get a feel of what you can expect to learn. If you think the art is not for you, try the others you mentioned you're interested in.
Good luck and I hope you find aikido as fulfilling as I do!