I've shot the judge a fair amount as a shooting buddy of mine owns one. I would pass on the judge and its variants for a multitude of reasons. Others disagree but I am in the camp that sees it more as a gimmick and marketing hype than a particularly good self defense gun.
Chris Costa (or perhaps it was Mr. Haley) remarked that they see shooters and newer shooters in particular have the fewest issues with the popular polymer framed striker fired pistols. I own and have had occasion to compare side by side a number of the most popular handgun designs (Glocks, sigs, various 1911s, kahr, Steyr, etc) my conclusion is that so long as any given exemplar functions reliably and shoots more or less to POA they are are well suited for defense and more up to that task than the vast majority of shooters. Just like everyone else I have my personal preferences which lead me to prefer certain guns over others. Anyone that acts like any of the major common pistols is a per se universally better choice than the others is someone I'd ignore.
I'd suggest as a starting point considering the following: Glock, S&W m&p series, Walther P99, Steyr (these are less well known but I'm a huge fan), XD, etc.
People fret over getting just the right gun, the fact is you could buy any of the above and it will more than likely serve you well. If you put in the effort you can become proficient with any of them.
I personally really like 1911s but I do see them as more of a race car than a some of the above. That is to say they can be more finicky (this is often because there is a whole spectrum or quality in how they are built and also some are built with other considerations in mind than being a defensive firearm) and/or require more work or maintenance. I'd be more confident in picking up a random glock than a random 1911. That said a good 1911 is very hard to beat IMHO.
There is no right answer, although there are IMO some wrong ones. I would go handle some guns and see what appeals to you. Shoot some different ones if you have a chance. I wouldn't worry too much about picking though.
I'd say the same for caliber. People fret over caliber. I used to be one that felt I needed to carry my .45. I have, through greater education, changed that position. I know believe that with quality ammo there just isn't enough difference to really spend time worrying about it at all. It is probably the least likely factor to be outcome determinative (that is unless a gun's caliber presents a problem for someone to shoot well, i.e. too much recoil). I've leaned towards 9mms lately, in part for ammo capacity but honestly more than anything because they are less ecpensive to shoot and I believe that the additional practice (not just shooting) is likely to be of more benefit than having a 357 sig, or a 45 ACP would be. Just my 2 cents.
In sum, any of the usual suspects and a number of the not so usual ones will do you just fine. The more important factor will be learinng how to use and run whatever you get well and putting in the effort to develop proficiency. The determinative factors for people are often matters of personal preference so go see what you like.