You asked about the Healey machanically compared to its contemporaries, I am not sure if you meant all or other british cars of the era, MGs and Triumphs, etc. For the most part they all have robust engines, solid cast iron units that will go on an on if maintained and not abused, I have driven british cars of the 50s and 60s for over 30 years, the 10-12 of those as my daily driver, I have never had a major engine mechanical failure (broken crank, bent valve, etc., they wear out eventually, but they tend not tobreak if you don't abuse them too bad). The Healey transmission is very robust, maybe even more so than contemporary Triumphs and MGs. The carbs and electrics and overdrives are the same design and manufacture across the board for all old LBCs, they can be finicky, particulalry if old and not well cared for, the best thing as mentioned is to drive the cars and work out the issues until you achieve a good degree of reliability.
As far as performance, Healeys and Triumphs are generally faster than MGs and will keep up with modern traffic, MGs on the other hand have a little more solid body/chassis and arguably better chassis and handling. From a fit standpoint Triumph TRs and MGBs do have a little more leg room than Healeys, if you are long legged (and I have heard some say big around the middle as well) the Healey can be a tight fit.
jaguars are another deal entirely, the carbs and electrics are basically the same, but a lot of the cars are based on 50s cutting edge (at the time) design, instead of the MG/TR/AH, which are all based on contemparary plain jane British sedans and such.
The dirving experience of the old MGs and Triumphs and MGs is great, direct mechanical feel everything instead of the insulated capsules that new cars generally are, much fun, but as mentioned, by the numbers the neighbors mini van not only is faster, but probably brakes and corners better by the numbers.
The cars are great fun to drive, work on and look at, you can work on them yourself if you are mechanically inclined, and, unless you are monetarily blessed you may not want to consider ownership unless you are inclined to work on them yourself, that is part of the fun for many of us.