I take it you're based in the UK, since all of these qualifications are based in the UK (but they are valid in other countries).
With the way they are raising the pension/retirement age, I think you would be spending a good 20 more years before employers consider you "past your prime".
CTA is very specialised on tax, and it's the highest qualification that you can get in tax in the UK (it's not an accounting qualification per se). It won't be valid abroad, unless you want to advise people abroad on UK tax. Since you did an AAT, I don't think you can directly apply for the ATT-CTA route (ATT = Association of Tax Technicians, not Association of Accounting Technicians). You can take the ATT qualification then directly apply for CTA, or you can complete any of the accounting qualifications that you have listed before applying for the CTA.
ACA is probably the highest accounting qualification you can get in the UK. It's broad and allows you to do quite a large number of things within accounting. If you want to go for a general accounting qualification in the UK, this would be the one I would recommend the most. It's also has strong affiliations with AAT, so you would get exemptions as well as extra support moving across into the ACA.
Should you decide not to stay in the UK, the ICAEW has mutual recognition agreements (MRAs) with accounting bodies in a number of countries e.g. US, Canada, Hong Kong, Singapore, India, etc. (you might need to check regarding the specific countries). If you want to practice accounting in these countries, you won't need to do another accounting qualification.
ACCA is the most widely recognised accounting qualification in the world. You can use the qualification to practice in 180+ countries (I think). I don't think it's as widely respected as the ACA in the UK, but it is a valid qualification to go into financial and management accounting with. Plus, you can use it to practice accounting in more countries than with ACA. There are a number of countries where ACCA isn't recognised, so you would have to check on that (Canada and US being 2 of them).
CIMA only allows you to work in management accounting or consulting. It would not allow you to practice financial accounting. If you're only intending to work in industry, then you're fine with any of the accounting qualifications, but I would say the material you learn in CIMA is far more useful. The material in CIMA is different from the other 2 accounting qualifications in the sense you would be using a more maths and require to do more mathematical calculations (although the maths still won't be anything beyond high school level).
Out of the 3 accounting qualifications, CIMA might have the fewest MRAs; it's recognised or transferrable in countries like the US and Canada, but you won't be able to use it in 180+ countries. You will need to check which countries CIMA is recognised in and with countries it has MRAs with.
From the sound of things, I would guess you're looking for something that's akin to either ACA or ACCA, where the qualification would probably allow you to do anything in accounting. I would personally do both (or multiple) qualification(s) so I have the most coverage around the world (and industries), but that's up to you whether you want to do that.
If you do intend to do more than one accounting qualification, bear in mind it doesn't mean you will have to do 13 papers for each qualification. If you complete an accounting qualification and then do a second accounting qualification, you should find you have 8-10 exemptions for your second qualification, so you will end up having to do another 3-5 papers.
For each accounting qualification, you have 4 exam cycles per year. Your Level 4 AAT should give you 3-5 exemptions. That usually means you end up having to do another 8-10 papers. Most people take 2 papers per cycle, so if you work hard, you should be able to become part qualified after 1 year or 18 months, assuming your pass everything the first time round.
With any accounting qualification, you will need your PER, which would come naturally if you work in an accounting role and under a supervisor who is qualified in the appropriate qualification (e.g. if you're an ACCA student, your supervisor needs to be ACCA qualified in order for your experience to count towards your qualification). In this respect, if you pass all of the papers in the qualification and you work in accounting, you would likely qualify as an accountant as part of the process i.e. you will become a fully qualified accountant whether you want to or not. Part qualified means you have passed all the exams, but not qualify for the experience.
You don't have to apply for senior roles should you choose not to, but becoming a fully qualified accountant would mean you have significant perks in income and independence (senior bookkeepers can be paid £20-25k but qualified accountants can go for £30-65k, depending on the specific role).
Do note, if you want to open your own practice, you would need to have relevant experience for X years in a practice in order to qualify irrespective of the accounting qualification. Having said that, if you already have an AAT level 4 + one year's experience under an AAT qualified person, you should be able to open your own bookkeeping practice anyway.
In terms of roles that take up the most hours, you are correct to assume that the more senior roles and the bigger firms (usually based in big cities, particularly London) tend to demand you to work longer hours. It's not true in all aspects though e.g. I have worked under financial directors who have worked the standard 35 hours per week, and in fact were doing fewer hours than me. If you're looking for a relatively small role, I would recommend looking at places in industry, companies based in towns, or small to medium sized accounting practices.
I don't know which qualification involves the least writing, but they all should be roughly the same. If you want something with more calculations, then CTA or CIMA might be something you might want to lean more towards. However, for what you specifically want and what your plans are, I would recommend looking into ACA first, and possibly ACCA as second.